Bush spoke with Palestinian President Mahmoud Abbas and Prime Minister Salam Fayed after a briefing by his top aides on the developments in Gaza, spokesman Gordon Johndroe said during a news briefing at Bush's Crawford, Texas, ranch.
In response to numerous rocket attacks on civilians, Israel initiated airstrikes against Gaza four days ago. More than 300 Palestinians have died and more than 650 people have been injured, the United Nations said. Hamas militants have responded with rocket and mortar fire from Gaza into Israel.
"President Bush and the two Palestinian leaders discussed their efforts for a sustainable cease-fire," Johndroe said. "They agreed that for any cease- fire to be effective, it must be respected, particularly by Hamas."
Bush reiterated his concern about Gazans, as well as U.S. willingness to assist in humanitarian efforts in Gaza, the spokesman said.
Johndroe said the Bush administration didn't want a cease-fire "for the sake of a cease-fire" only to watch violence resume in a few weeks.
"We have got to get a commitment from Hamas that they would respect any cease-fire and make it lasting and durable," Johndroe said.
Even though the United States doesn't communicate with Hamas, several governments -- such as Egypt, the Palestinian Authority and Jordan, for example -- in the region do, Johndroe said.
"These other governments ... who are in touch with the various Hamas factions will make it clear that ... this sort of violence is in no one's interest," he said.