Israeli Prime Minister Benjamin Netanyahu on Monday took a tough line toward an emerging Palestinian government ahead of a high-profile trip to Washington, saying "those that want to destroy us are not partners in peace."

Netanyahu reiterated a willingness to agree to a Palestinian state under certain conditions but made clear he did not believe it was possible if the Islamic militant group Hamas, which is set to join a Palestinian unity government with the Western-leaning Fatah movement, does not recognize Israel.

"I want to make peace with a Palestinian state that wants to end the conflict. I am not willing to accept a Palestinian state that wants to continue it," he said in comments that came a day after a series of deadly clashes with Palestinians demanding that refugees from the time of Israel's creation in 1948 and their descendants be allowed to return to their lost homes.

Netanyahu questioned the Palestinian commitment to peace after Sunday's confrontations along Israel's borders with Syria, Lebanon and Gaza. He also noted Hamas leader Ismail Haniyeh's calls for the end of the "Zionist enterprise."

"A Palestinian government, of which half declares daily that it is intent on annihilating Israel, is not a partner for peace," Netanyahu told his parliament Monday.

Hamas, a violent Iranian-backed group, is considered a terrorist organization by the U.S, EU and others because it has killed hundreds of Israelis in suicide bombings and other attacks. Hamas' official charter calls for the destruction of Israel.

Fatah and Hamas agreed last week to form a unity government to end a four-year rift that has left them with rival governments: a Hamas regime in Gaza and a Fatah-dominated administration in the West Bank. The Palestinians, who hope to establish a state in the two territories, say the new government will fill a caretaker role until new elections can be held next year.

Aides to Netanyahu described Monday's speech as a taste of the message Netanyahu will deliver at the White House on Friday.

President Barack Obama is expected to deliver a Mideast policy speech on Thursday, a day before his meeting with Netanyahu.

In his speech Monday, Netanyahu reiterated a long-standing list of demands from the Palestinians. Among them: recognition of Israel as the Jewish homeland, retaining major Jewish settlements in the West Bank and keeping all of Jerusalem under Israel control.

Saeb Erekat, the chief Palestinian negotiator, retorted that the Palestinians don't have a partner on the Israeli side. "Netanyahu has chosen settlements over peace," Erekat said.

The Palestinians claim all of the West Bank and east Jerusalem, areas captured by Israel in the 1967 Mideast war from Jordan, as parts of an independent state. They decline to recognize Israel as a Jewish state, fearing it would undermine their backing of the "right of return" of Palestinian refugees, a concept Israel rejects.

Palestinian President Mahmoud Abbas on Monday declared three days of mourning for 15 people were killed the day before in mass marches toward Israel's borders from Gaza, Syria and Lebanon.

Sunday's unrest occurred as the Palestinians marked the "nakba," or "catastrophe" — the term they use to describe their defeat and displacement in the war that followed Israel's founding on May 15, 1948 when Israel overcame the armies of surrounding Arab states as well as local Arabs who attacked after the Jewish state was declared.

Israel's U.N. ambassador, Meron Reuben, on Monday sent two letters of complaint about the border incidents to the Security Council.

"We expect the international community to take action to prevent further provocations," he wrote about the clash on the Lebanon border, warning that "such actions carry with them the serious potentional for escalation."

The letter charged that the storming of the Syrian border indicated that Syria was "seeking such provocations as a cynical distraction from other issues."