Iran's telecommunications agency announced that it has permanently suspended Google's e-mail services and plans to roll out a national e-mail service for Iranians.
The suspension of gmail comes as Iranian authorities have deployed force across Tehran to conduct last-minute security sweeps and warn residents to refrain from joining anti-government protests planned for Thursday, the 31st anniversary of the Islamic Revolution, Fox News reports.
According to reports, police have confiscated satellite dishes from residential rooftops and mobile phones are being searched and in some cases, taken by patrolling officials in certain areas of the capital where protests have erupted in the past.
Iranians have also reported widespread service disruptions of text messaging services.
Criticising the government over the move, state department spokesman P J Crowley said: "While information technologies are enabling people around the world to communicate like never before, the Iranian government seems determined to deny its citizens access to information, the ability to express themselves freely, network and share ideas."
"Virtual walls won''t work in the 21st century any better than physical walls worked in the 20th century. The Iranian people are dynamic and determined and will find a way to overcome the obstacles the Iranian Government puts in their way," he added.
Iranian authorities tasked with upholding Islamic values have also been scouring the streets, harassing people wearing green, the trademark colour of the opposition, according to witness accounts posted on opposition Websites.
The government typically orchestrates large, carnival-like rallies and demonstrations to mark the February 11 anniversary of the Islamic Republic.
For this year's events, opposition leaders have called for protesters to demonstrate against the regime. That has set the stage for clashes between authorities and demonstrators, who have taken to the streets repeatedly to protest the outcome of presidential elections in June.
Government officials, meanwhile, ratcheted up threats against any protests, vowing to confront demonstrators on the streets and calling for government supporters to turn out in large numbers.