According to the officials, the cyber operation, in late September, which impacted computing hardware, targeted the Islamic Republic's ability to "spread propaganda". When asked about the claimed attack today by Iran's Fars news agency, Iran Minister of Communications and Information Technology Mohammad Javad Azari-Jahromi replied, "They must have dreamt it".
The Pentagon declined to comment about the cyberstrike.
Tensions have soared in the Gulf in recent months with a series of attacks on oil infrastructure and tankers which have raised fears of a war between the arch-rivals. The U.S. blames a September 14 attack on Saudi oil fields on Iran, something Tehran denies.
Houthi rebels in Yemen on the other hand took responsibility.
Publicly, the Pentagon has responded by sending thousands of additional troops and equipment to bolster Saudi defenses - the latest USA deployment to the region this year.
It could take months to determine the impact of any cyber strikes, which are seen as a less provocative option than a conventional military assault.
It was unclear whether there have been other US cyber attacks since the one in late September.
The United States has blamed Iran for a series of attacks on ships in the Gulf of Oman this year, which it denies.
The ISI DG, who in the last week of September quietly visited Iran and Saudi Arabia, is believed to have played a major role in laying the ground for de-escalation in the Middle East. Officials said he would be the focal person for future contacts between Saudi Arabia and Iran. Iran has published images of damage done to the tanker.
Past year a Reuters investigation found more than 70 websites that push Iranian propaganda to 15 countries, in an operation that cybersecurity experts, social media firms and journalists are only starting to uncover.
If it actually took place, the cyberattack would be the second that the U.S. conducted against Iran in response to alleged attacks over the summer.
"A committee has been formed to conduct probe into the issue of the SABITI oil tanker which came under missile attacks off the Saudi coasts in the Red Sea and its findings will soon be handed over to the relevant bodies to make the required decision", Shamkhani stated.