US attack helicopters have struck several targets used by Iran-backed militants to fire rockets at bases housing American troops in northeastern Syria, the US military's Central Command said.

"US forces responded today to rocket attacks at two sites in Syria, destroying three vehicles and equipment used to launch some of the rockets," Centcom, which oversees US military operations in the Middle East, said in a statement.

Two or three suspected Iran-backed militants allegedly responsible for one of the attacks were killed, Centcom added.

Three US service members sustained minor injuries when several rockets hit both the Conoco and Green Village bases in Deir Ezzor, a strategic, oil-rich province bordering Iraq, yesterday evening.

The facilities are run by the Kurdish-led Syrian Democratic Forces, allies of the United States and other coalition partners that are maintaining a mission against the remnants of the Islamic State.

The strike comes a day after another US attack targeted facilities Washington said were used by Iran-backed militias in northeast Syria.

"The United States does not seek conflict with Iran, but we will continue to take the measures necessary to protect and defend our people," the Centcom statement said.