I can't find anything saying Winnie the Pooh is banned in Iran, so I think this is just made up. It does get censored in China because people were using him to reference Xi Jinping (they sort of look similar).
There was an app that censored the phrase "winnie the pooh" for a few months, he's sold at toystores all over china and you can look up images and videos of Disney Shangai's Winnie the pooh ride.
Hey, let's be reasonable and look at this from Irans point of view. Real porn is already illegal, and you see this perfectly tanned skinned bear shirt cocking you all day? How are we supposed to get any work done?