Israeli Prime Minister Benjamin Netanyahu said Sunday that his Gaza offensive would continue as long as necessary, a day after an Egyptian call for a ceasefire and new truce talks.

"Operation Protective Edge will continue until its aims are achieved... it may take time," he said of the Gaza Strip operation launched on July 8, in remarks broadcast by public radio.

An Israeli air strike killed two Palestinians in the enclave Sunday as militants kept up rocket fire.

The pace of Israeli raids was slower than Saturday when at least 60 strikes pounded Gaza, killing 10 Palestinians, mostly women and children, and bringing down a 12-storey apartment block.

But there was no sign of either side adopting the ceasefire Egypt appealed for on Saturday to allow negotiators to return to Cairo to thrash out the details of a durable truce.

Israeli aircraft hit 20 "terror targets" in Gaza Sunday morning, while militants fired at least 20 rockets or mortar rounds at Israel, the army said.

An Israeli strike on the western side of Gaza City killed two Palestinians and wounded five, emergency services said.

Since a previous round of frantic Egyptian diplomacy collapsed on Tuesday, shattering nine days of calm, 88 Palestinians and a four-year-old Israeli boy have been killed in the violence.

At a special cabinet session at the defence ministry in Tel Aviv, Netanyahu repeated his warning of harsh retribution for the death of an Israeli child on Friday in a rocket strike on a kibbutz near the Gaza border.

PM warns Lebanon, Syria

"Hamas is paying, and will continue to pay, a heavy price for the crimes it carries out," he said.

"I call on residents of Gaza to immediately leave any structure from which Hamas carries out terror activity against us. All such sites are a target for us."

At the funeral of Daniel Tragerman on Sunday, his mother Gila said she had seen the lively child as a future leader who could have brought peace.

"You are the love of my life, a perfect child, every mother and father's dream," she said.

Netanyahu also added a veiled warning to neighbouring Lebanon and Syria after overnight rocket fire into Israel.

"There is not and will not be any immunity for anyone who fires at Israeli citizens, and that is true for every sector and every border," he said.

Earlier on Sunday, five rockets fired from Syrian-controlled territory slammed into the Israeli-occupied sector of the Golan Heights but caused no casualties, the Israeli army said.

Late Saturday, a rocket fired from Lebanon struck northern Israel, causing damage but no casualties.

Israel has so far not responded to either attack.

In a statement on Saturday, the Egyptian foreign ministry urged "concerned parties" in the Gaza conflict to accept an open-ended truce and resume indirect negotiations in Cairo.

Previous ceasefires with fixed timeframes have failed to give Egyptian mediators shuttling between Israeli and Palestinian negotiating teams enough time to broker a deal acceptable to both.

Israel insists on full safety for millions of citizens who live in daily fear of rocket fire.

Egypt truce talks bid

Gaza's Islamist de facto ruler, Hamas, says any truce must provide for a lifting of Israel's crippling eight-year blockade of the territory and the opening of a seaport and airport.

But on Saturday, Defence Minister Moshe Yaalon told community leaders in the south that Israel now needed to look for a diplomatic solution to the rocket fire, adding that it would be doing so from a position of strength.

"I am convinced the other side in its condition needs a ceasefire more than we do," Yaalon said.

The invitation to new truce talks came after a meeting on Saturday between Egyptian leader Abdel Fattah al-Sisi and Palestinian president Mahmud Abbas.

"What interests us now is putting a stop to the bloodshed," Abbas said.

"As soon as a ceasefire goes into effect, the two sides can sit down and discuss their demands," he said, adding that, as in previous rounds of talks, Hamas would be represented in the Palestinian delegation.

Hamas spokesman Sami Abu Zuhri told AFP that "any proposal offered to the movement will be discussed".

Abbas held two rounds of talks in Qatar on Thursday and Friday with exiled Hamas leader Khaled Meshaal before heading to Cairo.

At least 2,105 Palestinians and 68 people on the Israeli side, all but four of them soldiers, have been killed since the conflict erupted nearly seven weeks ago.

The United Nations says 70 percent of the Palestinian victims were civilians, and that among the dead were 478 children.

Around 460,000 people have fled their homes in Gaza -- more than a quarter of the enclave's 1.8 million population.