"Preparing for all possibilities"
Asked if Israel might move from the mostly aerial attacks of the past four days into a ground war in Gaza, Prime Minister Benjamin Netanyahu said: "We are weighing all possibilities and preparing for all possibilities."
Casualties on both sides would probably rise sharply if Israeli forces stormed the largely urbanised enclave. A ground invasion of Gaza would be the first since a three-week war with Hamas in 2008-09 in which 1,400 Palestinians and 13 Israelis were killed.
Egypt's state news agency said that Egyptian President Abdel Fattah al-Sisi had met with Tony Blair, envoy for the so-called Quartet of United Nations, EU, Russia and United States, in efforts to secure a truce.
An Israeli government official said Blair had met with Netanyahu on Friday. "There are no serious contacts toward a truce. There are many proposals, but as long as Hamas keeps firing, Israel will keep fighting and will not discuss a truce."
Cairo played a crucial role in mediating a truce that ended an eight-day war between Hamas and Israel in 2012, when Egypt was governed by Hamas's Muslim Brotherhood allies.
Egypt's current military-backed government is locked in a feud with Hamas over the group's alleged support for jihadi militants in Egypt's Sinai desert - which Hamas denies. This could complicate Cairo's efforts at mediation.
Hamas spokesman Sami Abu Zuhri said: "We will not beg for calm and we continue to defend our people. Once we are offered a genuine, coherent and serious proposal, we will look into it."
Gaza medical officials said at least 82 civilians, including 25 children, were among the 125 dead so far from air strikes on the territory into which nearly 2 million people are packed.
Three militants and 15 other people, including two disabled women at a rehabilitation centre and a 65-year-old man, were killed by air strikes early on Saturday, doctors there said. An Israeli military spokeswoman had no immediate comment.
One of the dead in an air strike that killed six people in a Gaza street was identified as the nephew of Ismail Haniyeh, the Hamas political leader in the territory.
"Map of pain"
Israel says Hamas puts innocent Gazans in harm's way by placing weaponry and gunmen in residential areas. A senior Israeli military officer said aircraft had aborted "hundreds" of strikes to avoid collateral damage and that targets bombed were meant to impact Hamas fire capacity.
"We are dealing with a variety of families of targets. If there is a kind of a map, or a map of pain that the enemy sees, we create a lot of pain so that he will have to think first to stop the conflict," the officer said in a briefing to reporters.
Israel says it has hit more than 1,000 targets in Gaza.