At least two civilians and four militants have been killed in Israeli air strikes on Gaza, medics say, as cross-border violence continues.
The latest strike killed two militants east of Gaza City, an emergency services spokesman said.
Earlier, a 65-year-old man and his daughter were killed in a raid on a refugee camp, reports said.
Two Islamic Jihad members died in Khan Younis and a blast also killed a 15-year-old boy in Beit Lahiya.
Meanwhile, Egypt's parliament has called for the expulsion of the Israeli ambassador from Cairo and the recall of the country's envoy to the Jewish state, saying Israel was "the first enemy of Egypt and the Arab nation".
Israel says more that 240 rockets have been fired from the Gaza since Friday, injuring 35 people, one seriously.
On Monday, 40 rockets had struck southern Israel by late afternoon.
Two exploded near Gedera, only 40km (25 miles) south of Tel Aviv, and another struck the southern city of Ashdod, leaving a woman with moderate injuries, officials said.
The US has condemned the rocket attacks as "cowardly"; the Arab League called the Israeli air strikes "a massacre".
UN Secretary General Ban Ki-moon has said he is "gravely concerned at the latest escalation, describing rocket attacks on Israeli civilians as "unacceptable" and urging Israel to "exercise maximum restraint".
The cross-border violence was triggered by an air strike on Friday that killed a senior leader of the militant group, the Popular Resistance Committees (PRC), who Israel said had been planning an attack.
Militants in Gaza responded quickly by unleashing a barrage of rockets towards southern Israel, triggering further air strikes.
At least 25 Palestinians, most of them militants, have been killed in Israeli air strikes since then, sources at Gaza's main hospital say.
The 65-year-old and his daughter - whose age was given as both 30 and 35 years of age - died on Monday when a missile exploded outside their home in the Jabaliya refugee camp, in northern Gaza.
The 15-year-old died in an explosion early on Monday in Beit Lahiya, not far from Jabaliya, reportedly while he was on his way to school.
Palestinian officials blamed a drone strike, but an Israeli military spokesman later denied the claim, saying initial checks indicated that there had been no air strikes in northern Gaza at the time. Reporters also said they could see no evidence of an Israeli attack at the scene.
The two Islamic Jihad militants were meanwhile killed around Khan Younis early on Monday, one of them when a missile struck his motorcycle.
Later, two Palestinian militants whom Islamic Jihad identified as members of their group were killed during a raid east of Gaza City.
Hospital sources in Gaza said some 25 civilians - including children - were wounded when a rocket struck a house.
Islamic Jihad's military wing, the al-Quds Brigades, demanded that Israel cease fire and stop targeting militants pre-emptively.
"We warn the leaders of the enemy of the consequences of testing our patience. Our patience is limited and shall be turned into fire and destruction upon them,'' a masked spokesman told a news conference.
But Israel's chief military spokesman, Brig Gen Yoav Mordechai, said it would not end its "preventative targeting" operations.
"If the Qassam [rocket] fire ends, the Israel Defence Forces will not continue [strikes], but the Israel Defence Forces will continue thwarting any attempted terrorist attacks," he told Israel radio.
On Sunday, Israeli Prime Minister Benjamin Netanyahu warned that operations would "continue as long as necessary", saying he had given orders to "strike all those who plan on attacking us".
Leaders of Hamas, the Islamist militant group which governs Gaza, have said Egypt is working to try to bring an end to the violence.
"I expect matters will calm down," Mahmoud Zahhar told the Reuters news agency in Cairo. "The statements coming from [Israel] either in public or via mediators, especially Egypt, say that they do not want escalation."
"Hamas has not taken any decision now to escalate. It is trying with the Palestinian factions and the rest of the parties to reach a conditional truce, a truce conditioned on the Israeli enemy halting the aggression and pledging that targeting will not happen again," he added.
Islamic Jihad and the PRC - and not Hamas - have said they have been behind the rocket attacks.
The increase in violence has alarmed world powers trying to bring peace talks between Palestinians and Israelis back on track.
US State Department spokeswoman Victoria Nuland said Washington condemned "in the strongest terms" the rocket fire from Gaza, saying the attacks had "dramatically and dangerously escalated".
"We call on those responsible to take immediate action to stop these cowardly acts," she said.
The Arab League issued a statement accusing Israel of carrying out a "massacre" and calling for a tough stance from the international community against the Jewish state.
EU foreign policy chief Catherine Ashton said the bloc was "following with concern the recent escalation of violence in Gaza and in the south of Israel".
"It is essential to avoid further escalation and I urge all sides to re-establish calm," she said.
Mr Ban told the UN Security Council in New York: "I am gravely concerned at the latest escalation between Gaza and Israel and once again civilians are paying a terrible price."