It seems that the Iranian cyber police have find ways to check Iranians and Non Iranians if they have twitter or Facebook accounts. While entering Iran or by asking a visa for visit Iran in any embassy. Iranian Government is aware of Social Media.
This was not the case for Tunisia and Egypt Those governments did never pay attention to social media. They even where not aware of it #Syria now follows Iran and got advice on subject from #Tehran. To stop the influence of Social Media.
It’s for activists a must to do not use their real names in Facebook or Twitter and don’t mention other real names of activists. You can use Tehran as location.
It’s for you to decide it’s serous or not. But I can tell don’t try it.