Human Rights Watch, in a report published last weekend, said video evidence suggested Syrian forces were using Soviet-era cluster bombs during their conflict with rebel forces.
French Foreign Minister Laurent Fabius was quoted by Russia's state-run news agency RIA Novosti as saying the evidence was confirmed.
"Yes, we have evidence of the use of cluster bombs even though the regime denies that," he said.
Russian Foreign Minister Sergei Lavrov responded to the HRW report by saying there were "loads of weapons" in the area, noting it was difficult to ascertain the origin of the "large quantities" of weapons inside Syria.
China, Russia, the United States and Syria are among the countries that haven't signed a comprehensive ban on cluster bombs. Russia's military ties to Syria have been criticized over the course of the civil war there.
Fabius said the crisis could envelope the region unless Moscow gets in line to condemn the bloodshed in Syria.
"(Lavrov) says that we cannot get rid of Assad because that will lead to chaos and jihadists," said Fabius. "My response is that chaos is already there, and if you continue opposing regime change the danger is that extremists will increase their influence."