DAMASCUS (Sputnik) — The strike was carried out on Tuesday morning, with women and children among the victims, the source said.
The US-led coalition of more than 60 nations has been carrying out airstrikes against the Daesh in Syria and Iraq since the summer of 2014.
Manbij, located between Daesh's de facto capital of Raqqa and the Syrian-Turkish border, is a strategically important area for the terrorist group.
Syria has been mired in civil war since 2011, with government forces loyal to Syrian President Bashar Assad fighting numerous opposition factions and extremist groups. The Islamic State terrorist group, also known as Daesh in Arabic, is outlawed in the United States, Russia and many other nations.