"At 11:44 (0814 GMT) a distributed denial-of-service attack disrupted the internet services of some mobile and fixed operators for an hour," tweeted Sajad Bonabi.
A DDoS attack involves overwhelming a target's servers by making a massive number of junk requests.
"Connections have returned to normal following the intervention of Dejfa shield," Bonabi added, referring to Iran's so-called digital fortress against cyberattacks.
He did not elaborate on the source of the attack.
Bonabi is a board member at the ministry's Telecommunications Infrastructure Company, the sole provider of the country's telecommunications infrastructure.
Internet monitor NetBlocks confirmed Saturday's outage and said it was "consistent with a targeted disruption and no technical faults are evident at the present time".
Iran said in December it had thwarted a "highly organised cyberattack" targeting its e-government infrastructure.
Telecommunication Minister Mohammad Javad Azari Jahromi described the attack as "really massive" and "state-sponsored".
In late September, the country's energy sector was put "on full alert" to the threat of "physical and cyber" attacks a few days after Iran denied media reports its oil installations had been disrupted by a cyberattack.
Iranian authorities imposed a near-total internet blackout in mid-November when street violence broke out during demonstrations against a surprise decision to hike petrol prices.
The outage stemmed the flow of videos shared on social media of demonstrations or associated acts of violence.
Follow us on Twitter and Instagram to stay connected