Palestinian president Mahmud Abbas on Wednesday accused Israel of committing "genocide" in Gaza during its military campaign which has so far killed 43 Palestinians.

"It's genocide -- the killing of entire families is genocide by Israel against our Palestinian people," he told a crisis meeting of the Palestinian leadership in the West Bank city of Ramallah.

"What's happening now is a war against the Palestinian people as a whole and not against the (militant) factions.

"We know that Israel is not defending itself, it is defending settlements, its main project," said Abbas.

"We are moving in several ways to stop the Israeli aggression and spilling of Palestinian blood, including talking to Egyptian President (Abdel Fattah) al-Sisi and UN Secretary General Ban Ki-moon."

Egypt on Wednesday urged Israel and Hamas in Gaza to halt their spiralling conflict but played down hopes of a Cairo-mediated truce.

"There is no mediation, in the common sense of the word," said Egyptian foreign ministry spokesman Badr Abdelatty.

"Egyptian diplomatic efforts are aimed at immediately stopping Israeli aggression and ending all mutual violence. (Egyptian) contacts have not yet achieved a result."

Wednesday was the second day of Israel's Operation Protective Edge.

Israel warplanes have so far hit 550 targets in Gaza, and Hamas militants have hit back with 165 rockets, some of which struck Jerusalem and Tel Aviv and as far away as Hadera, 116 kilometres (72 miles) to the north of the coastal enclave.

Palestinian fatalities include militants but also women and children. More than 370 people have been wounded.