I would think that a lot of games are probably banned there. But this story is saying even bootleg copies of the game are being outlawed in Iran. Here is the Story:
EA's blockbuster shooter, which depicts military action in Iran, has reportedly been banned in the country. The report comes from The Daily Star (via Industry Gamers).
The report quotes an "unnamed deputy with the security and intelligence division of Iran's police" who said "All computer stores are banned from selling this illegal game."
It's important to note that Battlefield 3 has never officially been for sale in Iran. EA does not distribute games in Iran. However, as is common in many emerging markets, pirated or gray market copies of many Western games are readily available for purchase in stores. According to the article, many computer store owners in Iran had already declined to stock the game, anticipating an eventual ban on Battlefield 3 due to its sensitive subject matter. Apparently, raids have been conducted by Iranian police, cracking down on stores that had been "secretly" stocking the game prior to the ban.
There is also a backlash against the ban online. The Far news agency has reported that over 5,000 Iranian gamers have signed an online petition protesting the ban on Battlefield.