Colonel Ali Akbar Darvishi told the media that the militants were planning to carry out a terrorist operation in a busy tourist area in the port city of Nowshahr.
He added that the trio were identified and arrested through the efforts of security agencies and specialized police departments in Nowshahr.
Nowshahr, along the Caspian Sea and with a population of 150,000, is a popular tourist destination in western Mazandaran province.
The arrest is part of a broader effort by Iranian security forces to combat terrorists that normally infiltrate from neighboring countries.
In recent years, Iran has faced multiple threats from Daesh and other extremist groups.
In a significant counter-terrorism operation, Iranian security forces successfully dismantled a terrorist network affiliated with the foreign-backed terrorist Jaish al-Adl group in the southeastern border province of Sistan and Baluchestan on Thursday.
