At least 640 million dollars has been frozen inside the bank accounts.
A Rome court which issued the blocking order said that money from the accounts was being used to fund groups such as Hamas and Islamic Jihad as well as international terrorism in general.
The court announced that Tehran was spending 75 million dollars annually to sponsor and fund international terrorism.
The court looked at complaints by two American victims of an attack in Israel in 1999, found to be the work of groups backed by Iran.
It is unclear how long the assets freeze will last, however, an Iranian embassy official announced that the courts ruling was damaging to Irans interests.
