Videos uploaded to social media sites appeared to show victims of air strikes and barrel bombs by the Syrian air force against rebel-held territory in Damascus, Idlib and Aleppo.
It was not clear exactly when the strikes occurred but the videos showed wounded children being treated at a hospital in Damascus after an air strike as well as locals in the Saqarib area of Idlib attempting to extinguish a blazing vehicle in the road.
In Aleppo, a field hospital said to be exclusively for children was struck.
"We have children, we do not have terrorists or killers. This hospital is exclusively for children with inclusive clinics that include a section for women," said one doctor at the hospital.
The Syrian war, now in its fifth year, has killed more than 220,000 people. Of the country's roughly 23 million people, some 12.2 million are in need of humanitarian aid, including five million children, according to the UN.