Human Rights Watch is calling on Syrian forces to end what it calls the indiscriminate use of ballistic missiles in populated areas.
The U.S.-based group said Monday it has investigated nine apparent ballistic missile attacks this year that killed 215 civilians, mainly in the city of Aleppo and its surrounding province.
Aleppo is Syria's largest city, and has been among the key fronts in the civil war between President Bashar al-Assad and rebels trying to push him from power.
Human Rights Watch said there were no apparent military targets near where seven of the attacks took place, causing "significant civilian damage with no apparent military advantage."
It criticized the use of ballistic weapons, saying even if there are fighters in a given area, the weapons cannot accurately target them. The result, the group says, has been "devastating" to civilians.
Meanwhile, Assad has renewed his pledge to crush the rebels.
He said in a speech Sunday that "terrorism" cannot be solved through politics, and must be struck "with an iron fist."
The Syrian government has often used the term "terrorist" to describe the rebels opposed to Assad.
The conflict in Syria began as an uprising against Assad's rule in March 2011, and later developed into a civil war, leaving more than 100,000 people dead. Millions more have been displaced by the fighting.