The attacks were due to take place last week during the Qadr festival and on Jerusalem Day
Iran arrests 27 suspects over Ramadan 'terrorist' plot
Iran arrested 27 people suspected of being part of a “terrorist network” that was planning attacks to coincide with Ramadan, the intelligence ministry said on Tuesday.
“[The group] plotted to carry out terrorist operations in Tehran and some other important cities,” the ministry said in a statement on its website.
"They published pictures in cyberspace threatening the honourable nation of Iran with revenge and murder."
It said the attacks were due to take place last week during the Qadr festival and on Jerusalem Day, held each year in solidarity with the Palestinians.
The ministry said that a large number of weapons and ammunition were confiscated.
Iran has directly fought ISIS and Al Qaeda in Iraq and Syria.
Its Revolutionary Guards said on Sunday they had fought off three attempts by "terrorist groups" to infiltrate from neighbouring Iraq in recent days, leaving several dead.