Images on social media showed tents destroyed at the Kamouna camp near Sarmada in Idlib province, close to the Turkish border.
Some reports say the attack was by Syrian or Russian warplanes but this has not been confirmed.
The strike comes a day after the extension of a truce was confirmed.
The Syrian military and non-jihadist rebel forces had agreed to a temporary truce around the the city of Aleppo, following pressure from the US and Russia. READ MORE OF THIS REPORT