US President George W Bush has called Israeli leader Ehud Olmert who assured him Israel was taking "appropriate steps" to avoid civilian casualties in Gaza.

"President Bush got an assurance from Prime Minister Olmert that Israel is, as they have said they are doing, only targeting Hamas and that terrorist organisation," said White House spokesman Gordon Johndroe.

"I think the purpose of the call in general was to get an update from Prime Minister Olmert on where he sees the current situation right now as it relates to Gaza and to think about what the future steps are."

Johndroe said it was up to Hamas to take the first steps toward a ceasefire in Gaza by ending rocket fire into Israel.

"I think President Bush thinks that Hamas needs to stop firing rockets, and that is what will be the first steps in a ceasefire," Mr Johndroe said.

He added Hamas should not only stop firing rockets but "stop smuggling weapons in so they don't even have the ability to fire rockets".