The car was parked near the Amari Mosque in Kanaker, the channel reported. The Syrian Observatory for Human Rights, a British-based monitoring group, quoted activists as saying seven people had died.
The small town is under the control of President Bashar al-Assad's forces but there are rebels in the surrounding area. The province around Damascus has seen intense fighting during the two-year conflict.
Syria's civil war started with pro-democracy protests that were suppressed by government forces. An ensuing civil war has killed 90,000 people and drawn in regional powers hoping to sway the outcome of the conflict.
Assad's forces, spurred on by a series of recent battleground victories, have staved off rebel advances near Damascus and further south of the capital, in areas near the Jordanian border. Insurgents have used car bombs to target areas they are not able to push into with ground forces.
(Reporting by Oliver Holmes; Editing by Kevin Liffey)