Iran's foreign ministry on Thursday condemned as "organized terrorism" a vast Israeli operation launched in the Gaza Strip.

Iran "strongly condemns the criminal act of Zionist (Israeli) military forces in killing civilians," ministry spokesman Ramin Mehmanparast said in remarks published on the website of state broadcaster IRIB.

Egypt's President Mohammed Morsi rejected on Thursday what he called Israel's aggression in Gaza, saying it threatened to destabilize the region, while Cairo called on the US to stop Israel's strikes.

"The Israelis must understand that we do not accept this aggression, which can only lead to instability in the region," Morsi said in televised remarks, as Israeli air forces pummeled Gaza and militants fired rockets back in a deadly tit for tat.

President Michel Suleiman reiterated on Thursday calls for international pressure on Israel to engage in peace talks with Palestinians, saying war does not contribute to democracy in the region.

In a statement issued by Baabda palace, Suleiman condemned the “barbarous aggression launched on the Gaza (Strip) by Israel, which only uses the language of killing and destruction.”

Qatari Prime Minister Sheikh Hamad bin Jassem al-Thani warned that Israel's deadly raids on the Islamist-controlled Gaza Strip must not go unpunished, state news agency QNA reported on Thursday.

"This vicious attack must not pass unpunished," QNA quoted the premier as saying at a Wednesday meeting in Saudi Arabia of the six Gulf Arab nations and Russia.

Ahmed Jaabari, who was killed in an Israeli air strike on a car in Gaza City on Wednesday, was one of the most elusive and highest-ranking members of Hamas' armed wing.

Israel's Shin Bet domestic intelligence agency confirmed it targeted him in a joint strike with the army, saying he had been "directly responsible for executing terror attacks."

Israel is considering resuming its contentious practice of assassinating militant leaders in the Hamas-ruled Gaza Strip in an effort to halt intensified rocket attacks on Israel's south, according to defense officials.

That Israel might renew a practice that brought it harsh international censure is evidence of the tight spot Prime Minister Benjamin Netanyahu is in. With Israeli elections two months away, rocket barrages from Gaza are disrupting the lives of 1 million residents of southern Israel, pressuring the government to come up with an effective response.

The Israeli airforce launched three raids on targets in the Gaza Strip early Tuesday as military top brass weighed a stronger response to rocket fire from the Palestinian territory.

The air raids hit an uninhabited area to the west of Gaza City, without causing any casualties, Palestinian security sources and witnesses said.

The main Palestinian groups in Gaza, including Hamas and Islamic Jihad, said on Monday they were ready for a ceasefire if Israel "stops its aggression" against the territory.

"The Islamic and nationalist movement confirm that the response of the resistance depends on whether the Zionist aggression against our people is continued," they said in a statement released at a news conference in Gaza City.

The trial of four former Israeli military chiefs charged over a deadly 2010 raid on a Gaza-bound Turkish flotilla has been adjourned to February 21, the relief group that organized the mission said on Monday.

Israel has angrily denounced the case as a "show trial" and none of the four defendants have appeared in the dock at the Istanbul court where the trial opened November 6.

Israel is "prepared to escalate" its response to a flare-up of violence along its border with the Gaza Strip, Israeli Prime Minister Benjamin Netanyahu warned on Sunday.

"The world must realize that Israel won't sit by idly in the face of attempts to attack us. We are prepared to escalate our actions," he said at the start of his weekly cabinet meeting.