US Secretary of State Condoleezza Rice left Washington on Monday for Middle East on a mission widely expected to help defuse the conflict between Israel and the Hezbollah guerillas.
More than 360 people, mostly civilians, have been killed in Israeli military offensive against Lebanon, which began on July 12 after Hezbollah militias had seized two Israeli soldiers.
"We believe a ceasefire is urgent. It is however important to have conditions that make it sustainable," Rice said.
Prior to her departure, Saudi Arabia's Foreign Minister Prince Saud al-Faisal met US President George W. Bush in the White House on Sunday, calling for US intervention to stop the violent conflicts between Israel and Hezbollah in Lebanon.
Rice, who called on Hezbollah to halt rocket attacks on Israel and urged Israeli restraint, was scheduled to meet Israeli Prime Minister Ehud Olmert and Palestinian President Mahmud Abbas to discuss how best to end the fighting.
She was also due to attend an international conference on the Lebanon crisis in Rome on Wednesday before heading to an Asian security forum in Malaysia.
The United States and Israel said on Sunday that they were ready to support an international force led by NATO in south Lebanon to ease tensions.
Lebanese Prime Minister Fuad Siniora said the United Nations should take the lead if the international force is to be established.