Washington has warned its Israeli ally against any ground invasion of Gaza, as Egyptian officials say the US top diplomat is headed to the region to join efforts to end a week of deadly violence.

The White House stopped short of criticising Israel over the civilian casualty toll from its devastating air and artillery bombardment of the densely populated Palestinian enclave that has drawn flak from the UN and human rights watchdogs.

It said the Israeli government had the “right” and “responsibility” to defend its citizens against rocket attacks by its Islamist foe Hamas from its Gaza stronghold.

But it said even more civilians would be put at risk were Israeli Prime Minister Benjamin Netanyahu to heed hardliners in his governing coalition and send in troops and armour.

With Israel’s punishing air campaign in its seventh day, the death toll in Gaza hit 177, prompting growing calls for a ceasefire which have so far showed little sign of progress.

Ahead of an emergency meeting of Arab foreign ministers in Cairo, Hamas shot down hopes of a deal to end the violence, saying no serious moves had been made.

“Talk of a ceasefire requires real and serious efforts, which we haven’t seen so far,” Hamas MP Mushir al-Masri said in Gaza City.

“Any ceasefire must be based on the conditions we have outlined. Nothing less than that will be accepted,” he said, in a show of defiance in the face of the withering Israeli bombardment.

Israel says it’s not ready to countenance a ceasefire either, as it seeks to deal ever harsher blows to Hamas and stamp out its capacity to fire rockets deep into the Jewish state.

In a bid to add Washington’s weight to truce efforts, US Secretary of State John Kerry is to fly into Cairo on Tuesday, Egyptian state media reported.

There was no immediate comment from the State Department, with Israeli press reports suggesting Kerry would also visit Jerusalem and the West Bank city of Ramallah, headquarters of Palestinian president Mahmud Abbas.

While Arab states have demanded an immediate halt to Israel’s military campaign, with Jordan’s King Abdullah II urging Israel to “stop targeting civilians”, Germany’s top diplomat said Hamas should “immediately” halt its rocket fire.

Human rights groups say more than 75 per cent of the dead have been non-combatants. The UN agency for Palestinian refugees says more than a quarter of them have been children.