A firewall already prevents Iranians from accessing many Western sites. The latest move coincides with protests throughout the Muslim world - including some in Tehran - against an anti-Islamic film posted on Google's video-sharing site YouTube.
A government deputy minister announced the ban on Sunday on state television.
"Google and Gmail will be filtered nationwide, and will remain filtered until further notice," said an adviser to Iran's public prosecutor's office Abdul Samad Khoramabadi.
The announcement was also sent out as a text message on mobile phones. The unsecured version of the search engine, which is much easier to eavesdrop on, remains accessible.
Source: BBC News
