As the funeral was held for one of the three Israelis killed by a Hamas missile, world leaders called on the Palestinian militant group to stop its rocket attacks.
The US Senate unanimously passed a resolution expressing solidarity with Israel, supporting its right to act in self-defence.
Washington leaves no ambiguity over who it blames for the latest outbreak of hostilities.
"This is violence instigated by Hamas. You know, as we said very clearly in our statement yesterday that we extend our sympathies to the victims, innocent Israeli and Palestinian civilians that have been affected by this violence. But let's be very clear where the onus lies," said US State Department spokesman Mark Toner.
President Obama and British Prime Minister David Cameron have called on Israel to do everything to avoid civilian casualties in Gaza.
Russia has condemned Hamas rockets as "unacceptable" and Israeli airstrikes as "disproportionate".
The Middle East "Quartet" representative Tony Blair said several issues concerning Gaza needed to be resolved.
"The short term thing that needs to happen is that all of it is de-escalated back down and that means that the rockets stop because if the rockets carry on, the Israeli airstrikes will carry on and what happens, as we've seen, is that in that there will be innocent Israeli civilians killed and innocent Palestinian civilians killed," he said.
Amid widespread concern over the threat to civilians, the UN Secretary General is to visit the region next week.
Many are looking to Egypt to try to reduce tension. In the past it has acted as an intermediary between Israel and Hamas.
President Mursi has strongly condemned what he called Israeli aggression.
