Three U.S. officials told the Associated Press that the operation on Thursday evening disabled Iranian computer systems that controlled Iran's rocket and missile launchers.
The officials spoke on condition of anonymity because they were not authorized to speak publicly. Yahoo News first reported the cyber strike, France24 reports.
Two of the officials say President Donald Trump authorised the cyber strike even as he called off a conventional military response to Iran's downing of a U.S. surveillance drone.
Cybersecurity firms say Iran has increased its offensive cyberattacks against the U.S. government and critical infrastructure as tensions have grown between the two nations.