UN Secretary General Ban Ki-moon called on Saturday for an immediate ceasefire from both sides in the conflict, describing the violence as "unprecedented in recent decades."
The Israeli government is expected to consider later Saturday calling a 10-day unilateral ceasefire, a move that has already been dismissed by a Hamas representative in Lebanon.
More than 1,100 Palestinians have been killed since Israel launched a major military offensive in Gaza on December 27 in a bid to put an end to rocket attacks on Israeli territories from the Hamas-controlled enclave.
Dozens of schools run by the UN Relief and Works Agency, set up in 1949 to help Palestinian refugees, are sheltering around 40,000 Gaza residents due to the ongoing conflict.
Thousands more huddle in their homes, hoping to avoid stray bullets and shrapnel by staying away from windows.
"Fifteen of us - three families with eight children - crowded into our tiny kitchen. We sat like that through the night, in terrible fear," said a Russian citizen in Zahra, south of Gaza City, which had until now avoided Israeli military operations.
The Israeli Cabinet is expected to discuss on Saturday evening an end to the attacks, with the move possibly coming into immediate effect. However, troops would remain in Palestinian territory, and Hamas rejected Israel's plan as "an attempt to break the Egyptian plan to achieve a bilateral ceasefire."
"A unilateral ceasefire does not bring a withdrawal of the Israeli forces," said Osama Hamdan, Hamas's representative in Lebanon, warning that "confrontation will continue."
The UN secretary general said innocent civilians could not wait any longer for a halt in the military conflict. "We need an immediate ceasefire," Ban told the Lebanese parliament.
"We cannot wait for all the details, the mechanisms, to be conclusively negotiated and agreed, while civilians continue to be traumatized, injured or killed," he said.
"We have no more time to lose."
