Iranian state TV says authorities have disrupted "the biggest terrorist plot" to ever target Tehran.
Monday's report quotes the Intelligence Ministry as saying several suspects have been arrested in the plot to bomb the capital and other provinces.
It says authorities seized bombs and ammunition during the operation. The report didn't identify those arrested, though it called them "takfiris," a derogatory term in both Arabic and Farsi referring to Muslims who accuse others of being "nonbelievers."
Iranian authorities often refer to followers of the Sunni militant Islamic State (IS) group as "takfiris," though it isn't clear if this case involved the extremist group that holds territory in Iraq and Syria.
Shia power Iran has been helping both the Syrian and the Iraqi government in their battles against the IS group.