Iran has taken the next step beyond censorship to criminalize the use of social media, particularly Facebook.
Iran has long had one of the most strict and effective Internet censorship regimes, but still huge numbers of Iranians were able to skirt the blocking to access social media websites, generally under false names. Actually criminalizing the activity adds a huge chilling effect to those striving for free access to information and speech. Using Facebook is now not just difficult, but also dangerous.
Obviously it is unlikely that someone positing positive messages about Iran, or the mullahs, would be prosecuted. This is a big stick that can be swung at dissidents and any opposition.
Ironically many within the government, including president Hassan Rouhani, have and actively use Facebook and Twitter. Hypocrisy is never lacking in repressive governments.