"Militants from al-Nusra Front and Ahrar ash-Sham armed group conducted a mortar attack against the positions of [Syrian] government forces in the district of Ansar in Aleppo's southwest," a spokesman of the Russian center for Syrian reconciliation at the Hmeymim airbase said.
The attack with the use of mortars and multiple launch rocket systems was conducted from the Rashidin neighborhood in Aleppo, according to Russian military.
Earlier this month, Washington asked Moscow to direct its airstrikes solely at al-Nusra Front and refrain from targeting so-called "moderate" rebels, working with al-Qaeda's branch in Syria.
On Friday, Russian Foreign Minister Sergei Lavrov urged the US to convince those rebel groups which they support in Syria to leave areas where al-Nusra Front militants are present.