The United Nations Security Council was set for a showdown over Syria on Wednesday after Britain sought authorization for Western military action that Russia called premature.
Panetta said the US is using its diplomatic channels to relay worries about the fighting in the hopes that it will not broaden.
Around 5,000 people died in Syria`s civil war in August, making it the deadliest month since violence started 18 months ago.
UN Sec-Gen Ban Ki-moon has called on outside parties, especially countries in the Middle East, "to do all they can" to help end the Syrian conflict.
At least five people were killed and about 30 injured in a car bomb blast in the Jaramana neighbourhood of Damascus.
Day in Pics: 27th November
Showbiz World - November 27, 2014