JERUSALEM, Israel – Prime Minister Sharon threatened yesterday to freeze peace efforts if the Palestinian Arab leadership does not crack down on terrorist groups after a weekend suicide bombing in Tel Aviv killed four Israelis and wounded dozens.

At a Cabinet meeting, Israel decided to suspend a plan to turn control of five West Bank towns over to the Palestinian Arabs and free 400 more prisoners. Those gestures were agreed upon at a February 8 summit in Egypt, where Mr. Sharon and Palestinian Arab leader Mahmoud Abbas declared a truce.

The attack and the Israeli measures underlined the fragility of the truce and its vulnerability to violence by terrorists who oppose any accommodation.

A familiar pattern appeared in danger of re-emerging: a truce, a Palestinian Arab attack, Israeli retaliation, another Palestinian Arab attack – and ultimately the end of the truce and rekindled violence.

Mr. Sharon charged that Syria was behind the suicide bombing at a Tel Aviv night spot Friday, killing four Israelis – the first such attack since Mr. Abbas took office in January. Syria denied the allegation.

Islamic Jihad, a Palestinian Arab terrorist group with leadership in Lebanon and Syria, claimed responsibility Saturday after first denying any connection to the bombing.

At the beginning of the weekly Cabinet meeting, Mr. Sharon said Islamic Jihad carried out the bombing on orders from its leaders in Syria.

“We know this for certain,” he said, although he held the Palestinian Authority responsible as well.

“There will be no progress politically, and I repeat, no political progress, until the Palestinians carry out a determined campaign to destroy the terrorist groups and their infrastructure,” Mr. Sharon said.