"The massacre committed by Israel in Qana this morning shows the barbarity of this aggressive entity. It constitutes state terrorism committed in front of the eyes and ears of the world," Assad said in remarks carried by state news agency SANA.
Meanwhile, US Secretary of State Condoleezza Rice has abruptly breaken off her diplomatic mission in the region and is returning to Washington,a US official said Sunday.
Rice had planned to head back to the United States on Monday morning after discussions on ending the fighting between Israel and Hizbullah in southern Lebanon.
The US official, who spoke on condition of anonymity about the diplomatic situation, said Rice would work from Washington on a UN Security Council resolution to end the crisis.
A draft resolution circulating among Security Council members calls for an immediate halt to fighting and seek a wide new buffer zone in south Lebanon monitored by international forces and the Lebanese army.
Kuwait has meanwhile announced that it will donate donate USD 300 million for reconstruction in Lebanon, the government said Sunday.
The International Committee of the Red Cross and United Nations agencies working in Lebanon will get a further USD 2 million ), the Kuwaiti cabinet said in a statement after its weekly meeting.