According to Bleeping Computer, the App Store is no longer available in Iran. The ban took place sometime around noon GMT today.
The report states that the ban seems to be IP based, as an Iranian security researcher, Meysam Firouzi, was able to access the App Store by way of a VPN, despite having an Iranian-based account details. This means that users in the country are required to use a VPN even if they attempt to create a US-based App Store account.
This ban appears to be IP-based. Meysam Firouzi —an Iranian security researcher— told Bleeping Computer that he successfully connected to the App Store while using a VPN, despite having Iran-related details set on his account.
Apple has not officially commented on the issue. However, the company previously banned applications created by Iranian developers from the App Store in the country due to U.S. law. At the time, Apple stated:
Under the U.S. sanctions regulations, the App Store cannot host, distribute or do business with apps or developers connected to certain U.S. embargoed countries.
It’s worth noting that Apple is doing no business in the country, with no official Iran App Store. However, millions of iPhones are smuggled into the country and Iranian developers use other App Store countries to distribute apps to users.
Source: 9to5mac