The Russian Defence Ministry says none of its planes were near the refugee camp in northern Syria when the site was hit on Thursday.
"We've closely studied the objective airspace monitoring data for May 4 and 5, 2016. Neither Russian nor any other aircraft were flying over Sarmada," ministry spokesman Igor Konashenkov said, according to Russia's Tass news agency.
Konashenkov said the bombardment of the al-Kamoun camp, near the town of Sarmada, could have come from al-Nusra Front rebels using rocket launchers. Russia is key ally of the Syrian regime.