Syrian activists said government troops shelled the central city of Homs on Friday.
The London-based Syrian Observatory for Human Rights said online footage showed tanks firing at residential neighbourhoods.
The government has not commented.
Media access to Syria is heavily restricted, making it almost possible to verify claims by both sides.
Homs has been under an intensified attack since February the fourth, but there are also reports of fighting in Deraa.
President Bashar Assad’s 11-month crackdown has sparked anger worldwide, with the UN General Assembly condemning the violence on Thursday.
Now Syrian embassies have been become the focal point for protesters.
In Cairo, Egyptians and Syrians marched together to call for diplomatic ties to be severed between their countries.