Israeli troops have shot dead three Palestinians in raids in the West Bank, the army and local residents say.
The two militants were killed in a raid on a house in Nablus
Two militants from the al-Aqsa Martyrs' Brigades group were killed on Sunday morning in Nablus. A teenage boy was shot later near Ramallah.
The Israeli army said the teenager had been preparing to attack soldiers.
Six Palestinians were killed in the West Bank and the Gaza Strip on Saturday, in the worst flare-up of violence in weeks.
The Israeli army said all of its attacks had been in response to tangible threats.
But Hamas spokesman Fawzi Barhoum said the events of the past two days meant that Palestinians should be prepared for a "new round of confrontation" with Israel.
Palestinian Information Minister Mustafa Barghouti said the attacks meant it was time to review whether the bi-weekly meetings between the Palestinian and Israeli leaders should continue.
"This up-scaling of attacks during the last 24 hours makes us almost sure that there is no Israeli partner for peace," he said.
"We are clearly seeing here a situation where Israel is abusing these meetings to cover up its crimes."
Heavy gun battle
Israeli troops killed the two members of the al-Aqsa Martyrs' Brigades after surrounding a building in Nablus in the early hours on Sunday.
Saturday's strike on Gaza was in response to rockets fired into Israel
The militants were shot dead during a heavy gun battle, the army and Palestinian residents said.
Several hours later, the teenager was killed by Israeli forces in a village near Ramallah.
The Israeli army the shots were fired as the teenager prepared to attack soldiers.
"They [the soldiers] spotted a man about to throw a petrol bomb, fired at him and saw that he was hit," an Israeli army spokesman was quoted as saying by Reuters news agency.
Palestinian residents said the boy had been throwing stones at Israeli troops.
Israel and Palestinian militants have observed a truce since November, although Israel has launched some raids, and militants in Gaza have fired some rockets into Israel.
The Israeli army says the ceasefire still holds but the government says it still has the right to take defensive measures against rocket attacks.
The militant Islamic Jihad group has said it will not adhere to the truce while Israel continues to carry out raids in the West Bank.