Syria’s state-run SANA news agency said one child had been killed, and that at least three other people were wounded.
The strikes, confirmed by the Pentagon in a statement, mark the second such US attack on Iran-backed militias in Syria since president Joe Biden took office.
They targeted operational and weapons storage facilities at two locations in Syria and one in Iraq, the Pentagon said in a statement.
The facilities were used by militia groups, including Kataeb Hezbollah and Kataeb Sayyid al-Shuhada, two hardline Iraqi military factions with close ties to Tehran, the Pentagon added.
“These facilities are utilized by Iran-backed militias that are engaged in unmanned aerial vehicle (UAV) attacks against US personnel and facilities in Iraq,” said Pentagon spokesman John Kirby.
US interests in Iraq have come under repeated attack in recent months, with the United States consistently blaming Iran-linked Iraqi factions for rocket and other attacks against Iraqi installations housing its personnel.
In February, US strikes on facilities in east Syria used by Iran-backed militia groups left more than 20 fighters dead, according to the Observatory.
The Pentagon said the strikes were retaliation for a rocket attack in Iraq that killed one civilian contractor and wounded a US service member and other coalition troops.