A power plant and other industries in southern Iran have been targeted by the Stuxnet computer worm, an Iranian civil defence official says.
But the cyber attack has been successfully rebuffed and prevented from spreading, Iranian media report.
Iran's nuclear enrichment efforts were hit hard in 2010 by the Stuxnet worm, which was also blamed for problems at industrial plants and factories.
Tehran accused Israel and the US of planting the malware.
Provincial civil defence chief Ali Akbar Akhavan said Iranian industry was constantly being targeted by "enemy cyber attacks" and companies in Hormozgan province had recently been infiltrated, the semi-official Isna news agency reported.
"The Bandar Abbas electricity supply company has come under cyber attack," he told a news conference. "But we were able to prevent its expansion owing to our timely measures and the co-operation of skilled hackers."
The Bandar Abbas plant, on Iran's southern coast in the Strait of Hormuz, is said to supply power to neighbouring provinces as well as Hormozgan.
Iran has regularly claimed success in defeating computer viruses, such as Stuxnet and Flame, which have affected its industries.
In April, a malware attack on Iran's oil ministry and national oil company forced the government to disconnect key oil facilities, including the Kharg Island oil terminal that handles most of Tehran's exports.
Late last year, Iran said some of its computer systems were infected by the Duqu spyware which was believed to have been designed to steal data to help launch further cyber attacks.
The attacks have affected its energy exports as well as its controversial uranium enrichment programme, which Western countries suspect is aimed at constructing nuclear weapons. Tehran insists it is solely for peaceful purposes.
The biggest cyber attack so far was from the Stuxnet worm, believed to be the first known virus specifically targeted at infrastructure such as power stations.
In 2010, Iran accused the West of trying to disrupt its nuclear facilities with the Stuxnet worm.
Researchers estimated that five industrial processing organisations in Iran were hit repeatedly between June 2009 and April 2010 by the worm which they believed had been created by a "nation state" in the West.
Iran said centrifuges used in uranium enrichment had been sabotaged and the UN nuclear watchdog said the enrichment programme had been temporarily brought to a halt.
Reports suggested that the worm had infected the personal computers of staff at Iran's first nuclear power station at Bushehr.
In September this year, Israeli Prime Minister Benjamin Netanyahu told the United Nations General Assembly that time was running out to stop Tehran having enough enriched uranium to build a nuclear bomb.
US President Barack Obama has said the US will do "what we must" to stop Iran acquiring nuclear weapons.