The filtering appears aimed at tightening Internet censorship and limiting online expression.
"Kalame" says the move signals a decision by the Iranian establishment to block service providers and exclude blogs en masse instead of one by one.
The Iranian government filters tens of thousands of websites and blogs, and in recent years a number of bloggers have ended up in jail for their writings.
Blogging is extremely popular among Iranians, especially among young people.
-- Golnaz Esfandiari