Western nations on Friday pushed Egypt to persuade Palestinian militants to end rocket attacks from Gaza and backed Israel's right to self-defense, laying bare a new divide with the Arab world.
While they deplored civilian casualties on both sides since Israel launched a military assault against the Gaza Strip on Tuesday, the West stressed the onus was on Hamas to halt rocket fire into southern Israel.
"Israel has the right to protect its population from these kinds of attacks. I urge Israel to ensure that its response is proportionate," European Union foreign policy chief Catherine Ashton said.
She echoed hopes that Egyptian Prime Minister Hisham Qandil, who crossed into Gaza for a brief visit Friday, "will be able calm the situation."
Washington has reached out to Egypt's new Islamist leaders as well as to allies such as Turkey to use their sway with Palestinian leaders.
US Secretary of State Hillary Clinton, who is traveling in Asia, has spoken twice with her Egyptian counterpart, Mohammed Amr, since the start of the operation, with the second conversation taking place after Qandil's Gaza visit.
"In all of the conversations that she has had... we all agree on the need to de-escalate this conflict," State Department spokeswoman Victoria Nuland said.
Clinton was also expected to be in contact with "countries with influence, to try to maximize the pressure we can bring to bear on Hamas to cease and desist," Nuland added, although she said the top US diplomat had not yet spoken with Palestinian Authority leaders in the West Bank.
But she again stressed the US position that "Israel has a right of self-defense" and refused to be drawn on reports that the Israeli army was preparing for a land invasion of the Gaza.
Speaking at Gaza City's Shifa hospital after seeing the bodies of those killed in an alleged Israeli air strike, Qandil vowed to step up Cairo's efforts to secure a ceasefire.
"Egypt will not hesitate to intensify its efforts and make sacrifices to stop this aggression and achieve a lasting truce," he told reporters on Friday.
But he placed the blame squarely on what he called Israel's "aggression."
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Egyptian President Mohamed Morsi also branded the Israeli assault in which 23 Palestinians have been killed as a "blatant aggression against humanity," the official MENA news agency said.
And he vowed: "Cairo will not leave Gaza on its own."
Egypt, which in 1979 became the first Arab country to sign a peace treaty with Israel, often plays a mediator role between Israel and Hamas, and Morsi has been fielding calls from world leaders over the rising violence.
French President Francois Hollande expressed "deep concern" in a phone call and "stressed the role Egypt could play to cut the tensions," the president's office said.
Russian President Vladimir Putin also told the Egyptian leader that Moscow supported Egypt's efforts to halt the violence, the Kremlin said.
"The Russian head of state underlined the need to stop the armed confrontation and called on the sides involved in the conflict to exercise restraint and stop military actions resulting in civilian deaths," it said.
Saudi King Abdullah, whose country is a heavyweight in the six-nation Gulf Cooperation Council, told Morsi "that things must calm down and reason and wisdom must reign over passionate reactions," the state news agency SPA said.
The Palestinians' traditional allies have reacted angrily to Israel's onslaught.
Turkish Prime Minister Recep Tayyip Erdogan accused Israeli officials of ordering the air strikes as an electoral move ahead of January's vote, in which Prime Minister Benjamin Netanyahu is running for re-election.
"Ahead of this (new) vote, the current leadership once again chose the route of striking these innocent people of Gaza for made-up reasons," Erdogan said, quoted by the Anatolia news agency.
US President Barack Obama called Erdogan on Friday, and both leaders voiced concern that the "continued spiral of violence jeopardizes prospects for a durable, lasting peace," the White House said in a statement.
Pakistan also condemned the Israeli air strikes on Gaza Strip and vowed to stand by the people of Palestine against "Israeli aggression," branding it a violation of international law.
British Prime Minister David Cameron meanwhile called on Netanyahu "to do all he could to avoid civilian casualties" and prevent more violence.