In May, rock legend Elvis Costello canceled his gig in Israel. Then, in June, a group of unionized dock workers in San Francisco refused to unload an Israeli ship. In August, a food co-op in Washington state removed Israeli products from its shelves.

The so-called “boycott, divestment, and sanctions’’ movement aimed at pressuring Israel to withdraw from land claimed by Palestinians has long been considered a fringe effort inside the United States, with no hope of garnering mainstream support enjoyed by the anti-apartheid campaign against South Africa of the 1980s.

But in recent months, particularly after an Israeli raid on a flotilla delivering supplies to Palestinians, organizers are pointing to evidence that the movement has picked up momentum, even as Israelis and Palestinians are moving toward a new round of peace talks.

“Peace talks have been going on for decades and all they have resulted in are more dispossession,’’ said Nancy Kricorian, a New-York-based staff member for Code Pink, an antiwar group that launched a boycott of the cosmetic company Ahava because its products are manufactured in an Israeli settlement.

Kricorian, who grew up in Watertown, said Code Pink experienced increased interest by groups wanting to endorse the boycott during the Israeli operation in Gaza last year, and again since a May 31 Israeli raid on a flotilla left nine pro-Palestinian activists dead. Ahava did not respond to an e-mail request for comment.

Susanne Hoder, a member of a “divestment task force’’ set up by the Lawrence-based New England Conference of the United Methodist Church, said she believes activists will continue efforts until the Israeli military leaves the West Bank.

“Slowly but surely people are starting to recognize that some action is needed,’’ she said.

Her task force supports divestment from 29 companies it says are involved in the Israeli occupation of the West Bank, including Motorola and Caterpillar, but not from Israel itself.

The movement has gained energy from a Palestinian boycott announced in May of products made by Israeli settlers, but it also has sparked a backlash from Israeli lawmakers, who are now considering a bill that would bar non-Israelis involved in “boycott divestment sanctions’’ efforts from entering Israel for 10 years.

An additional measure being considered would allow settlers to sue activists inside Israel and the West Bank who help organize boycotts. If the measures pass, they could be used against US activists, the Palestinian Authority, and Israeli groups such as Boycott from Within and whoprofits.org, a website that lists settler products.

Jonathan Peled, spokesman for the Israeli Embassy in Washington, said it is unclear whether the bills will pass. He called the various boycott and divestment efforts in the West Bank and the United States “regrettable and counterproductive,’’ especially as Israeli and Palestinian leaders are set to begin peace talks in Washington next month. It is unclear whether the Palestinian boycott will continue throughout the peace talks.

But activists in the United States and Europe — where the movement has much more widespread support — say such actions provide a much-needed outlet to people who want to end the conflict.

“We used to lobby the US government, the Israeli government, and the Palestinians to do something,’’ said Sydney Levy, of Jewish Voices for Peace, a California-based group that collected 17,000 signatures since June asking investment firm TIAA-CREF to divest from companies involved in the occupation. “But now we realize that we can take action on our own. We are only waiting for ourselves.’’

TIAA-CREF said in a press release that it would not alter its investment policy.

The movement is such a hot-button issue that the sale of stock in Israeli companies often sparks unfounded speculation. Earlier this month, after a blogger reported that Harvard University sold $41.5 million in holdings in a number of well-known Israeli companies, the university had to issue a statement explaining its investment strategy and assuring the public that it had not “divested from Israel.’’

Last year, after student activists at Amherst-based Hampshire College told reporters that they had successfully lobbied for the sale of holdings in an Israel-related mutual fund, the university swiftly announced that the sale was not political.

Boycott activists say they are not discouraged by the lack of popular support, noting that the successful boycott of apartheid South Africa took decades to come to fruition. But that boycott had strong support among African-Americans, while boycotts against Israeli companies face passionate opposition from many Jewish Americans, who have mobilized to oppose such efforts.

“Their goal is to brand Israel the new South Africa,’’ said Jonathan Haber, a Boston consultant who started the website DivestThis.com to fight against the movement. “Israel is not an apartheid state.’’

Hussein Ibish, of the Washington-based American Task Force for Palestine, said the “boycott, divestment, sanctions’’ movement had no chance of becoming mainstream inside the United States as long as it targets Israel. But he said actions aimed at Israeli settlements “had a shot’’ at garnering popular support, especially now that the US government is pressing Israel to stop building settlements in the West Bank on land that US, European, and Arab officials hope will become a Palestinian state.

“There isn’t a big constituency in the United States for being hostile to Israel, but I think there is potentially a huge constituency for pressuring Israel to end the occupation,’’ said Ibish.

For decades, Israel has provided tax incentive and subsidies for settlers who move to and open businesses in the West Bank, a territory the size of Delaware that the Israeli military took control of in 1967, when it won a war against Arab nations.

Today about 17 percent of the area’s 2.5 million people are Israeli settlers, while the rest are Palestinians, according to US estimates. International law forbids a country from moving its civilians into occupied territory. But Israel maintains that the West Bank is disputed territory exempt from that provision.

Hoder, 58, a former communications director, said the goal of the New England Methodist divestment task force is to help end the conflict, not to harm Israel. Earlier this year, she led a Methodist fact-finding mission in the West Bank. This summer, the task force helped persuade two more Methodist groups to pass divestment petitions, bringing the total number to 11 out of 62.

Hoder said she became an activist in 2002, after a group of Palestinian YMCA officials came to visit Rhode Island. She traveled to see Israel and the West Bank for herself for the first time in 2004.

“I was shocked,’’ she said of hardships that the occupation brought in Palestinian daily life. “I came back with a clear sense that as churches, we shouldn’t be sitting on the sidelines.’’

In 2005 — a year after the church’s worldwide governing body voted to oppose the Israeli occupation — Hoder and other church activists established the task force, which recommends that individuals divest from 29 companies, including Motorola, which sells security surveillance systems for settlements and checkpoints; Caterpillar, which sells bulldozers that tear down Palestinian homes; and Veolia, a French transportation company involved in building a light rail system between the settlements.

Spokeswoman Tama McWhinney said Motorola is “concerned about any issues that shareholders raise’’ but will “continue to provide communications systems to more than 70 countries around the world in accordance with their laws.’’ Jim Dugan, spokesman for Caterpillar, said strict US antiboycotting laws prevent US companies from participating in boycotts.

“We expect our customers to use our products in . . . ways consistent with human rights,’’ he wrote. A spokesman for Veolia was not available for comment.

The Methodist church’s largest investment body, the General Board of Pension and Health Benefits, still holds stock in companies on the list, including Motorola, Caterpillar, and Veolia.