The attack crippled computers used to control rocket and missile launches.
The United States launched cyber attacks against Iranian missile control systems and a spy network this week after Tehran downed an American surveillance drone, US media reported on Saturday.
US President Donald Trump ordered a retaliatory military strike against Iran after the drone shootdown but then called it off, saying the response wouldn't be "proportionate" and instead pledged new sanctions on the country.
But after the drone's downing, Trump secretly authorized US Cyber Command to carry out a retaliatory cyber attack on Iran, The Washington Post reported.
The attack crippled computers used to control rocket and missile launches, according to the Post, which cited people familiar with the matter.
Yahoo cited two former intelligence officials as saying the US targeted a spying group responsible for tracking ships in the strategic Strait of Hormuz, where Washington has blamed Iran for two recent mine attacks on oil tankers.
The Post said the strikes, which caused no casualties, had been planned for weeks and were first proposed as a response to the tanker attacks.
US defense officials refused to confirm the reports.
"As a matter of policy and for operational security, we do not discuss cyberspace operations, intelligence or planning," Defense Department spokeswoman Heather Babb told AFP.
The Joe Biden administration said on Thursday it was ready to revive a 2015 agreement between Iran and world powers that former president Donald Trump abandoned in 2018 before reimposing sanctions on Iran.
“If Iran comes back into strict compliance with its commitments under the JCPOA, the United States will do the same and is prepared to engage in discussions with Iran toward that end,” a joint statement from the four nations said.
Trump made the request during an Oval Office meeting last Thursday with his top national security aides, including Vice President Mike Pence, Secretary of State Mike Pompeo and chairman of the Joint Chiefs of Staff, the official said.
Sheikh Mohammed Bin Zayed expressed his thanks to Sheikh Tamim Bin Hamad for his congratulations and the sincere fraternal feelings he showed, wishing the brotherly State of Qatar and its people further progress and development.
Sheikh Sultan’s statement reads, “The Ruler of Sharjah congratulates Mansour Bin Zayed Al Nahyan on his appointment as Vice President."
Sheikh Mohammed said, “I congratulate my brothers Sheikh Hazaa, Sheikh Tahnoun, Sheikh Mansour and Sheikh Khaled Bin Mohamed for the confidence in the President of the State. In you and your brothers, the leaders of the new generation, the march continues.”