Palestinian youths throw stones towards Israeli border police officers in the village of Issawiya in Arab East Jerusalem in protest of the Israeli air strikes in Gaza December 27, 2008. [Agencies]

Asked if the United States would back a continuation of the retaliatory strikes by Israel, Johndroe said: "The US doesn't want to see any more violence. I think what we've got to see is Hamas stop firing rockets into Israel. That's what precipitated this."

At his ranch, the president took a call from King Abdullah of Saudi Arabia, who wanted to discuss the violence that began eight days after a six-month truce between Israel and the militants expired.

"The United States strongly condemns the repeated rocket and mortar attacks against Israel and holds Hamas responsible for breaking the cease-fire and for the renewal of violence in Gaza," Rice said in a statement. "The cease-fire should be restored immediately. The United States calls on all concerned to address the urgent humanitarian needs of the innocent people of Gaza."

Israeli warplanes launched counterattacks on dozens of security compounds across the Hamas-ruled territory in unprecedented waves of airstrikes. Most of those killed were security men, but an unknown number of civilians were also among the dead.

Hamas said all of its security installations were hit, threatened to resume suicide attacks, and sent at least 70 rockets and mortar shells crashing into Israeli border communities, according to the Israeli military. One Israeli was killed and at least six people were hurt.

With so many wounded, the Palestinian death toll was likely to rise. The strikes caused widespread panic and confusion in Gaza. Some of the Israeli missiles struck in densely populated areas as children were leaving school, and women rushed into the streets frantically looking for their children.

Johndroe said the US was concerned that humanitarian needs were being met in Gaza. He urged Israel to avoid striking civilians, but he refrained from commenting specifically on positions that had been hit on the ground.

"I know they are targeting security and Hamas headquarters facilities," Johndroe said. "We urge them (the Israelis) to avoid civilian casualties."

"The message from the United States is that Hamas is a terrorist organization that is firing rockets into Israel and they fired them onto their own people as well," Johndroe said, noting reports he'd seen about the death of two Palestinian girls. "Hamas has done nothing for the people of Gaza."

The offensive has sparked angry protests throughout the Arab world. British Prime Minister Gordon Brown, the Vatican, the UN secretary-general and special Mideast envoy Tony Blair called for an immediate restoration of calm. The Arab League scheduled an emergency meeting Sunday to discuss the situation.