Col. Amin Yamini, the commander for the western Tehran suburb of Shahriar, said the attacks were being planned for the 10-day Ashura rituals that begins on September 22.
On June 7, Daesh militants attacked the Iranian parliament in Tehran and the shrine of Imam Khomeini, killing 17 people and injuring many more. Riyadh has denied any involvement.
The Wednesday report from semi-official YJC.ir says the suspect was in contact with 300 IS members and was planning attacks during Shiite ceremonies across the country next month.
The Revolutionary Guards fired several missiles at Daesh bases in Syria on 18 June in response to that attack.
According to Yamini, the Guards tracked the Islamic State organizer, who had a cell phone and satellite phone, and set up a meeting with him in the western Tehran suburb of Andisheh by posing as Islamic State members. When the person showed up, he was arrested.
"So far, very important information has been collected from the Daesh element's phone, and he remains under investigation", he said.