Four people were killed in the blast
The radical Palestinian group said 34-year-old Samir Alu Suleiman, from Jenin in the West Bank, carried out the mission.
The attack took place as Israeli Prime Minister Ariel Sharon left for the US for talks with American President George W Bush, scheduled to be held on Monday.
The BBC's Jeremy Cooke in Jerusalem says the attacks will mean Mr Sharon will be in an uncompromising mood for the meeting with Mr Bush.
Mr Sharon said he held Palestinian leader Yasser Arafat "directly responsible" for what he described as an act of "murder and terror".
He is insisting on a full seven-day ceasefire before considering any move to implement the Mitchell peace plan.
Early on Friday three members of Islamic Jihad were arrested by an Israeli army unit in the West Bank town of Hebron, according to Palestinian sources.
The Palestinian Authority said it was working "in its full capacity" to stop attacks against Israeli civilians, and had ordered its security agencies bring perpetrators "to justice".
The Authority also called on Israel "to stop its assaults and to stop assassinations which only increases tension".
'Enormous explosion'
Thursday's suicide blast took place on a bus was travelling on a motorway between Hadera and Afula, witnesses said. The bus was near an Israeli military base.
A man who was driving along the same route told Israel radio that he heard an "enormous explosion" as a bomb had "apparently blown up inside the vehicle".
Another witness, Emanuel Biton, described the bomb as ripping the bus to pieces, with "things flying everywhere".
The bus was not crowded at the time of the blast, otherwise the casualty figure would have been much higher.
Envoy determined
US envoy Anthony Zinni said on Friday that the latest violence would not deter him from his goal of achieving a truce and restarting peace talks.
"The groups that do this are clearly trying to make my mission fail," he said.
"I am determined not to let that happen."
Mr Zinni and his fellow envoy William Burns have been sent by US Secretary of State Colin Powell in the hope of mediating a successful ceasefire between the two warring sides.
Correspondents said the blast could only further complicate what is already an ambitious task.
Israeli government spokesman Avi Pazner said the attack showed the Palestinian Authority was trying to undermine the peace mission by "doing nothing to stop terrorism".
But the Palestinian Authority said in a statement it "condemns the attack on Israeli civilians...and reaffirms that it is working in its full capacity to put an end to all sorts of attacks against Israeli civilians".
Earlier on Thursday, two Palestinians were shot and killed by Israeli troops at a roadblock in the northern West Bank.
Israel's army said soldiers shot at a car when it tried to run into them. A spokesman expressed regret that a second Palestinian was killed by mistake.
In a second West Bank incident, Palestinian gunmen killed a soldier in a drive-by shooting.