Syrian forces loyal to President Bashar al Assad have taken control of the town of Tel Kalakh, close to the Lebanese border.
The recapture of Tel Kalakh marked another gain for Assad after the capture of the former rebel stronghold of Qusair this month.
The US Secretary of State John Kerry has reiterated a diplomatic solution must be found to end the bloodshed in Syria.
Speaking on a visit to Kuwait, Kerry said military intervention by foreign forces was out of the question.
Earlier this month, Washington offered to provide assistance for the rebels.
Israel’s Prime Minister Benyamin Netanyahu has said repeatedly that his country has no desire to be drawn into the fighting.
On a trip to the Golan Heights, however, Netanyahu told soldiers, “we’re not seeking to challenge anyone, but no one will harm the State of Israel without a response – a strong and resolute response.”