Iran denied having any link to sites targeted by the United States in Syria, Iranian foreign ministry spokesperson Nasser Kanaani said on Wednesday, according to the ministry's telegram channel.
On Tuesday, the U.S. military said it carried out a strike in Syria's Deir al-Zor against infrastructure facilities used by groups affiliated with Iran's elite Revolutionary Guards Corps (IRGC).
"The U.S. attack on Syrian infrastructure and people is a violation of Syria's sovereignty and territorial integrity. The sites targeted had no links to the Islamic Republic," Kanaani said.
A U.S. military spokesman told Reuters that eight U.S. fighter jets, four F-16 and four F-15E, hit 9 targets in Syria.
The spokesman added that there were no reports of civilian casualties.
At the White House, spokesman John Kirby said the strikes targeted ammunition depots and other military facilities.
"As before, we don't seek escalation," Kirby told reporters in Washington.
This is not the first time U.S. warplanes have struck Iran-backed forces in Iraq and Syria. The United States hit operational and weapons storage facilities at two locations in Syria and one in Iraq in June last year.
U.S. forces first deployed into Syria during the Obama administration's campaign against Islamic State, partnering with a Kurdish-led group called the Syrian Democratic Forces. There are about 900 U.S. troops in Syria, most of them in the east.
Iran-backed militias established a foothold in Syria while fighting in support of President Bashar al-Assad during Syria's civil war.
(Reporting by Dubai Newsroom. Additional reporting by Idrees Ali and Phil Stewart in Washington; Editing by Jon Boyle and Chizu Nomiyama)