At least two Katyusha rockets were fired at a military base hosting US forces, the agency said.
One explosion can be heard in footage emerging from the scene.
The rocket strike comes days after a US airbase near the Koniko gas field in northeastern Syria was targeted by a single drone, which was ultimately engaged by a air defense and struck down without further incident.
The twin strikes unfolded as renewed focus was shed on the official removal of US troops from Iraq, a feat that is expected to take place as part of a "two phase transition plan." The US has about 2,500 troops in Iraq. Another 900 troops are said to be in Syria, considered an illegal occupation under international law.