Palestinian leader Mahmoud Abbas (search) said Monday that a five-month-old truce with Israel can still be salvaged though negotiations with the militant groups Hamas and Islamic Jihad.

But after four days of violence imperiled the February cease-fire, Abbas warned the militants they must refrain from acting on their own.

"Nobody has the right to take the law into his own hands, nobody," he told foreign reporters at his headquarters in Gaza City (search).

The militant groups agreed to abide by the truce during a March meeting with Abbas in Cairo. He said he still hoped that with Egyptian help, the militants can be persuaded through negotiations to hold their fire.

"I don't think that diplomacy has failed completely," Abbas said. "We are still working very hard ... to get a full commitment to the truce now or pretty soon."

Israeli troops massed outside Gaza over the weekend, and Israeli Prime Minister Ariel Sharon (search) said he had given the army a free hand to halt an onslaught of Palestinian mortar and rocket fire. The troop buildup came after six Israelis were killed last week, five in an Islamic Jihad suicide bombing and one in a Hamas rocket attack. The attacks abated somewhat on Monday.

Abbas blamed Israel for starting the violence, listing incidents in which Israeli forces killed Palestinians, but he said Palestinians should "take decisions together by consensus rather than any one faction acting on its own."

Israel has repeatedly condemned Abbas' policy of trying to persuade the militants to quit attacks, saying there is no alternative to disarming them.

The Palestinian leader said he hoped to avoid gunbattles between the Palestinian Authority and militants, such as those over the weekend that killed two bystanders.

"We don't accept going to civil war," he said. But he did not rule out force, either. "We hope and pray we won't have to shoot anyone."

Egyptian mediators in Gaza met for a second day with leaders of militant groups Monday, telling them they had no right to retaliate on their own for perceived Israeli truce violations.

Abbas said he hoped the Egyptians would be able to "cool down the situation in Gaza."

The Palestinian leader has said that maintaining the truce is especially important given Israel's plans to withdraw from the Gaza Strip next month.

"These shootings and rockets will only hinder the process of withdrawal and the future process of negotiations," he said. "We want this withdrawal to be clean and to be final."