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."