Israel will immediately suspend airstrikes over southern Lebanon for 48 hours, after an airstrike in Qana killed about 60 civilians, many of them children.
The State Department says Israel is coordinating with the United Nations to allow a 24-hour window for civilians to leave the region if they wish.
The Qana attack is the single deadliest bombing in Lebanon since hostilities began between Israel and Hezbollah almost three weeks ago.
The attack has drawn international condemnation, and sparked protests at UN facilities in Beruit and Gaza.
Israeli Prime Minster Ehud Olmert has expressed "great sorrow" over the bombing, but also says Qana was a "hub for Hezbollah"
An emergency session of the UN security council is meeting at this hour — Secretary General Kofi Annan criticized Washington for not pressing for an unconditional cease-fire.