Elsewhere in the capital, fighters were due to withdraw "within hours" from the Palestinian refugee camp of Yarmuk following a truce struck last evening to end deadly fighting, a Palestinian official said.
Regime forces took parts of the strategic Qalamun region near the border with Lebanon in April, but some 2,000 rebel fighters withdrew to the hills from where they have launched guerrilla attacks.
Fourteen fighters from the powerful Shiite Hezbollah group have been killed in the area over the past two weeks, the Syrian Observatory for Human Rights said.
An officer interviewed by the channel said "the army has cut the route off to terrorist groups who try to return to the region from time to time. The operation is continuing until the whole of the Qalamun area has been cleansed.
"This land will be a cemetery for all terrorists who decide to return."
President Bashar al-Assad's regime refers to the armed opposition inside the country as "terrorists", without distinguishing between different groups.
He said the rebels had launched a counter attack "and succeeded in retaking their positions and expanding their presence".
Since the Syria conflict erupted in March 2011, more than 162,000 people have been killed and millions displaced.
Meanwhile fighters were expected to exit the embattled Yarmuk camp in southern Damascus "within hours", a Palestinian official told AFP in the Syrian capital today.
The pullout is part of a truce agreed between the PLO and gunmen "with the approval of the Syrian government", he said, adding that the fragile ceasefire went into force at 1500 GMT yesterday.
