Palestinian militant group Islamic Jihad says it carried out Friday's Tel Aviv suicide attack in which four died.
Israel says Palestinian efforts to stop terror have failed
The bombing was the first serious blow to a ceasefire agreed by Israeli and Palestinian leaders earlier this month.
But Islamic Jihad leaders in Gaza still deny any involvement, suggesting a split between factions, says the BBC's Barbara Plett in Jerusalem.
Seven people have been detained by Israeli and Palestinian forces over the bombing, which injured about 50 people.
The leader of the Palestinian Authority Mahmoud Abbas condemned the attack, and promised to "hunt down" those responsible.
An Islamic Jihad official in Damascus told news agencies the bombing was in retaliation for Israel's violation of the truce.
"The calm period with the [Palestinian] Authority was an agreement for a month and that has ended," the official, who gave his name as Abu Tareq, told the Associated Press.
"Israel has not abided by the pacification period. This is the main reason that led to this operation," he added, without giving details.
Islamic Jihad officials in the West Bank and Beirut echoed the claim, but the group's leadership in Gaza continued to deny that it was responsible.
Our correspondent in Jerusalem says the statements could suggest a divide between Islamic Jihad's inner circle, based in Gaza, and its outside leadership in Syria, which is said to have more influence over cells in the West Bank.
Israeli soldiers raided the village of Deir al Ghusun, just north of the West Bank town of Tulkarem, on Saturday morning and imposed a curfew.
Two brothers of the bomber, identified by the Israelis as 21-year-old Abdullah Badran, were arrested, as well as the local imam.
Palestinian sources say the bomber was a member of the al-Aqsa Martyrs' Brigade, but also recruited and funded by Lebanon-based Hezbollah militants - though a Hezbollah spokesman in Beirut has denied this.
Palestinian police separately arrested two people over the blast.
The two men held by Palestinian security forces were also arrested in the Tulkarem area. One source described them as Islamic Jihad militants.
"The Palestinian Authority will not stand silent in the face of this act of sabotage," Mr Abbas said in a statement after meeting security chiefs.
Mr Abbas blamed a "third party" but went no further.
Israeli Prime Minister Ariel Sharon was expected to meet security chiefs to discuss a response.
A top Sharon adviser, Raanan Gissin, told the BBC that the Palestinian Authority must take "the necessary, concrete steps to dismantle the terrorist organisation, collect the illegal weapons, make the necessary arrests".
US Secretary of State Condoleezza Rice called for the Palestinians to take "immediate, credible steps" to find those behind the attacks.
Militant attacks had fallen away in the days after Israel and the Palestinian Authority reached a truce at a summit in Egypt on 8 February.
It was not known if Badran was acting on his own
The bomber set off a device as people queued to get into the club, reportedly after security guards spotted him and kept him out.
The attack happened at the entrance to the Stage club on Herbert Samuel Street, close to the promenade, Tel Aviv police chief David Tsour said.
Israeli media report the blast occurred at 2315 (2115 GMT).
Clubs in the area have been attacked by Palestinian militants in the past, notably the Dolphinarium disco, where a bomber killed 21 in 2001.