Explosions have rocked the Syrian capital, Damascus, on Saturday, and the northern city of Aleppo as security forces try to push rebels from their remaining strongholds.
The government says it has regained control of all of the capital. The French news agency reports a brigadier general told journalists that rebels had resorted to hit-and-run tactics against security forces.
Activists say an entire district became a battleground in Aleppo on Saturday. An army helicopter fired machine gun rounds and ground troops shelled targets in an attempt to oust rebels from their positions.
The opposition Syrian Observatory for Human Rights says more than two dozen people were killed in anti-government-related violence across Syria on Saturday.
In another development, Iranian state media reports say 48 Iranian nationals who were aboard a bus in Damascus have been kidnapped. Iran says efforts are under way to free the nationals, described as religious pilgrims.
In recent years, hundreds of thousands of Iranians have traveled to Syria to visit the Sayeda Zeinab mosque, a holy Shi'ite shrine in Damascus. Iranians have been targets for kidnap gangs several times since Syrian rebel groups began their mass uprising against President Bashar al-Assad more than 17 months ago.
Syrian rebels come mainly from the country's Sunni Muslim majority, while most Iranians practice Shi'ite Islam.
Some information for this report was provided by AFP and Reuters.