Israeli troops and Palestinian police have arrested seven people in connection with Friday's suicide bombing outside a Tel Aviv nightclub.
Israel says Palestinian efforts to stop terror have failed
Israeli soldiers detained five people near the West Bank town of Tulkarem, including two brothers of the man identified as the suicide bomber.
Palestinian police separately arrested two people over the blast, which killed four people and injured about 30.
Palestinian leader Mahmoud Abbas has pledged to punish the perpetrators.
It was the first attack since Israeli and Palestinian leaders agreed earlier this month to end violence.
"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.
"We will follow and track down those responsible and they will be punished accordingly."
Mr Abbas blamed a "third party" but went no further.
Other Palestinian officials have blamed Hezbollah, the Lebanese militant organisation.
However, Hezbollah issued a statement in the Lebanese capital, Beirut, denying the allegations as "completely devoid of truth".
All Palestinian militant groups have denied responsibility.
The BBC's James Reynolds in Jerusalem says it is in everyone's interests to show that this was an attack by a group from outside the Palestinian territories.
Israeli Prime Minister Ariel Sharon was also 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.
Israeli soldiers raided the village of Deir al Ghusun, just north 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.
It was not known if Badran was acting on his own
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.
The two men held by Palestinian security forces were also arrested in the Tulkarem area. One source described them as Islamic Jihad militants.
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.