Syrian rebels claimed on Sunday that they have launched an offensive to "liberate" the country's largest city of Aleppo.
But in Damascus, government troops backed by helicopter gunships wrested back control of rebel neighbourhoods.
The rebel attack on Aleppo, Syria's commercial hub and traditionally a bedrock of support for President Bashar Assad, illustrated the lack of any central rebel strategy, coming as government forces appeared to be regaining control of the capital.
Rebels fighting in Aleppo claim to be in full control of the Salaheddine district.
In Damascus, rebels reported attacks by government forces and helicopters in athe neighbourhoods of Mazzeh and Barzeh, causing heavy casualties.
But Syrian state TV said that troops were mopping up the remnants of "terrorists."
Television showed images of calm streets in Damascus and workmen cleaning up rubble in the once rebel-held Midan neighbourhood.
However, despite government efforts to present an image of calm in the capital, Malaysia's government said it was shutting its embassy in Damascus and evacuating more than 130 students and diplomats, while Italy ordered its citizens to leave the country.
The escalating fighting in Syria has put the country's neighbours on edge, particularly Israel.
Prime Minister Benjamin Netanyahu said Israel was monitoring for signs that chemical weapons or missiles might make their way into the hands of anti-Israeli militants.