"This week, Blizzard tightened up its procedures to ensure compliance with these laws, and players connecting from the affected nations are restricted from access to Blizzard games and services," read the statement.
Unfortunately, said Blizzard, the same sanctions meant it could not give refunds to players in Iran or help them move their account elsewhere.
"We apologise for any inconvenience this causes and will happily lift these restrictions as soon as US law allows," it added.
Although the block on Wow has been imposed by Blizzard, other reports suggest a wider government ban might have been imposed.
Players of Wow and other games, including Guild Wars, said when they had tried to log in they had been redirected to a page saying the connection had been blocked because the games promoted "superstition and mythology".
Blizzard said it had no information about Iranian government action against online games.