The Syrian army and allied forces confronted an attack launched by forces affiliated with the Syrian Democratic Forces alliance on villages in the northern countryside of Deir Al Zor province on Tuesday, state news agency (SANA) reported.
The SDF is a Kurdish-led alliance in north and east Syria which worked with the U.S.-led coalition against Islamic State.
Spearheaded by the Kurdish People's Protection Units (YPG) and including Arab fighters, it holds a quarter of Syria, including oil fields and areas where some 900 U.S. troops are deployed.
Turkey, Syria's northern neighbour, considers the YPG and the SDF by extension to be "terrorist" groups.
Reporting by Clauda Tanios