In some of the strongest Palestinian condemnation of an attack during more than four years of bloodshed, President Mahmud Abbas on Saturday blamed outsiders opposed to his two-week-old ceasefire with Israel.
"We will bring them to justice. We will not allow anyone to sabotage the ambitions of our people," Abbas said.
The bombing late on Friday claimed the first Israeli casualties since a ceasefire was agreed between Abbas and Israeli Prime Minister Ariel Sharon at an 8 February summit.
Eight Palestinians have been killed and 36 more wounded in the same period.
Israeli troops pushed into the West Bank village of Dair al-Ghusun before dawn, arresting five men, including two brothers of the suspected bomber. Palestinian forces later picked up three men thought to have links to fighters.
"We have arrested two people for interrogation in connection with this attack," Interior Minister Nasr Yusuf, who was appointed on Thursday, said.
He refused to identify the pair detained, but a Palestinian security source said the two men had been arrested in the Tulkarim area of the northern West Bank.
"We will bring them to justice. We will not allow anyone to sabotage the ambitions of our people"
According to Muain Shadid, Aljazeera's correspondent in Palestine,
Israeli forces claimed that 21-year-old university student Abd Allah Badran's family had said their son was the bomber of the Tel Aviv operation.
The soldiers raided the house of his brother Said Shilbawi Badran, 21.
The soldiers arrested Badran's two brothers Muhammad and Bilal, one of whom works for the Palestinian police, Shadid said.
They also arrested the imam of the town's mosque and other residents. Shadid reported no Palestinian factions confirmed Abd Allah Badran's identity or claimed any links to him.
Words not enough
Israeli officials said the bombing proved that the Palestinian strategy of trying to win over the fighters to ratify the truce had failed and tougher action was needed.
"Words are not enough. We must see action," said Gideon Meir of Israel's Foreign Ministry. "We must see arrests, collecting illegal weapons from those terrorist organisations ... . The only language they understand is force."
"Words are not enough. We must see action"
Gideon Meir, Israeli Foreign Ministry official
A 25-nation conference in London this week is to look at ways to help Palestinians improve security forces and build Israeli confidence in their ability to prevent attacks.
Sharon was to weigh Israel's response to the bombing at a meeting with security chiefs on Saturday.
Responsibility for the attack, the first bombing in Israel in nearly four months, remained unclear.
A cell of the Islamic Jihad group in the West Bank claimed the attack, but the faction's leadership in the Gaza Strip denied any knowledge and said it would continue to maintain calm. Other mainstream groups also denied any role.
The Israeli media have hinted at
Hizb Allah's hand in the attack
Israeli media said Lebanese Hizb Allah fighters, who have recently come under Palestinian suspicion, may have had a hand in the bombing to try to stop peace efforts. There was no immediate comment from the Iranian-backed group.
Abbas said "there is a third party which wants to sabotage this process" but did not point a finger at Hizb Allah.
US Secretary of State Condoleezza Rice demanded that Palestinian leaders find those responsible and "send a clear message that terror will not be tolerated".
Washington has stepped up efforts to revive the peace process after Abbas was elected to succeed late President Yasir Arafat with a pledge of non-violence.
Rice is demanding Palestinian
leaders find those responsible
Russia called on the Palestinian leadership to take whatever steps are needed to halt attacks after the Tel Aviv attack.
But in a statement, the Foreign Ministry expressed Russia's condolences for relatives and friends of the victims and said the attack should not be allowed to derail efforts to rekindle the Middle East peace process.
"Moscow condemns in the strongest terms this terrorist crime and calls on the Palestinian leadership to take all steps to prevent extremist acts," the statement sent to news organisations said.