After intense diplomatic efforts and threats of military action, Israel appeared Sunday to have stymied an attempt to challenge its naval blockade of the Gaza Strip, with nearly all boats in a planned aid flotilla confined to ports in Greece.

Israeli officials pronounced themselves satisfied with efforts to block the flotilla, which have averted a confrontation at sea. Last year, Israeli naval commandos boarded a similar flotilla and killed nine people in clashes on a Turkish ship, drawing international condemnation that forced Israel to ease its land blockade of Gaza.

“This time, the flotilla was dealt with wisely,” Finance Minister Yuval Steinitz told Israel Radio, hailing what he called “a great success.”

Of 10 boats that were expected to sail for Gaza last week, eight remain in port after Greek authorities banned their departure Friday. One of the vessels, carrying American activists, was turned back by the Greek coast guard when it tried to sail without clearance. The boat’s captain was arrested.

The propeller shaft of a boat carrying Irish activists was damaged in a Turkish harbor last week, after similar damage to another ship docked in Greece. The activists accuse Israel of sabotage; the Israeli military has declined to comment. A lone boat that sailed June 25 from the French island of Corsica is at sea.

Flotilla organizers said Sunday that they are planning legal and political action to try to overturn the Greek sailing ban, and they called the flotilla project a success for drawing attention to conditions in Gaza.

One activist, Dimitris Plionis, told the Associated Press that there would be “some action” at the beginning of the week. AP reported that Plionis did not provide specifics, but he noted that “ships are free to go to other locations.”

Israeli Defense Minister Ehud Barak said the governments of Greece, Cyprus and Turkey had taken measures against the flotilla as a result of “very extensive activity by the Foreign Ministry, the Prime Minister’s Office, and ourselves,” with Israeli officials using “contacts we have with the Cypriot, Greek and European leaderships.”

Israeli Prime Minister Binyamin Netanyahu has been cultivating ties with Greece since his nation’s relations with Turkey soured after last year’s deadly flotilla raid. In a speech last week, he mentioned Greek Prime Minister George Papandreou by name in thanking world leaders for their efforts to head off the flotilla.

Cyprus has banned departures from its shores to Gaza, and a Turkish charity that had been the main organizer of the flotilla pulled out its ship last month, after a public call by Turkey’s foreign minister to put off the maritime protest.

Along with their concerns about a potentially violent confrontation with Israeli forces, Greece and Turkey are preoccupied with other worries. Greece is struggling with a deep economic crisis, and Turkey has been coping with a refugee influx on its border with Syria, whose crackdown on an anti-government uprising has drawn criticism from Ankara.

The Israeli military has warned that it is prepared to use force if necessary to maintain its naval blockade of Gaza, which it says is meant to stop the smuggling of arms into the territory, which is controlled by the militant Islamist group Hamas.

In a statement issued Saturday, the quartet of Middle East mediators — the United States, the United Nations, the European Union and Russia — urged delivery of supplies to Gaza through “established land crossings” where cargo can be checked. It called on governments to “use their influence to discourage additional flotillas, which risk the safety of their participants and carry the potential for escalation.”

Mark Regev, a spokesman for Netanyahu, said the flotilla organizers were left politically isolated. “These activists received no legitimacy,” he said, adding that with Israel easing restrictions on goods entering Gaza, claims that the boats were bringing needed aid to the territory were recognized as unfounded.

Medea Benjamin, an activist from Washington who was with the U.S. ship, said that even without reaching its destination, the effort to sail had succeeded in refocusing international attention on “the plight of the people of Gaza.”

“We have still managed to show the lengths Israel is willing to go to stop a ragtag group of 10 ships and 300 unarmed peace activists from reaching Gaza,” Benjamin said by telephone from Athens. “This is not over. We’ve certainly won the propaganda war.”