Israel's bombardment of Gaza claimed its 121st Palestinian life on Saturday as Hamas pounded central Israel with rockets and Washington offered help brokering a truce.
As the battle between Israel and Hamas militants entered its fifth day, diplomatic efforts to end the hostilities gathered pace.
Overnight, US President Barack Obama phoned Israeli Prime Minister Benjamin Netanyahu to express concerns and to offer his help in resolving the crisis.
"The United States remains prepared to facilitate a cessation of hostilities, including a return to the November 2012 ceasefire agreement," the White House said, referring to a truce which ended the last major confrontation between Israel and Hamas.
But Egypt, which has played a key role in mediating previous ceasefire agreements, said its efforts were falling on deaf ears.
Neither of the warring sides appeared to have any interest in backing down.
After weeks of rocket fire on its south, Israel lost patience and was bent on dealing a fatal blow to Hamas, with Netanyahu insisting that Israel would continue its offensive until rocket fire out of Gaza is halted.
Saying he had had "good conversations" with world leaders in recent days, including President Barack Obama and European leaders, he added: "No international pressure will prevent us from acting with all power."
And Ismail Haniya, Gaza's former prime minister and the most senior Hamas official in the enclave, also ruled out any end to hostilities. "Israel is the one that started this aggression and it must stop, because we are simply defending ourselves," he said.
Hamas' armed wing, the Ezzedine al-Qassam Brigades, has kept up a steady stream of rockets deep inside Israel, with sirens sending people fleeing for shelter in Jerusalem, Tel Aviv and in the northern city of Haifa.
On Friday morning, three Gaza rockets were shot down over Tel Aviv by the Iron Dome anti-missile system as the Brigades claimed their militants had fired M75 missiles at Israel's main international airport.
Israeli strikes killed more than 30 Gazans on Thursday, and another eight died in three separate strikes on Friday, raising the overall death toll to 100.
Early on Saturday 16 were killed in air strikes, medics said. A later strike killed three in the eastern Tufah neighbourhood of Gaza City.
The raid came shortly after two people were killed in a strike that hit a charitable association for the disabled in Beit Lahiya in northern Gaza, bringing the toll on the fifth day of violence to 121. More than 500 have been injured.
So far, no one in Israel has been killed, and only 10 people have been hurt, two of them seriously, medics said.
A 61-year-old man was badly injured yesterday when a rocket struck a petrol station in the southern port of Ashdod, after a soldier was severely wounded in a mortar attack the night before.