Only legal and registered VPNs are allowed to be used in the country which maintains strict control over what citizens can view online.
Iranian authorities have blocked the use of virtual private networks (VPNs) used to get around the country's extensive Internet filters.
Ramezanali Sobhani-Fard, the head of parliament's information and communications technology committee, told the Mehr news agency the regime is currently blocking unauthorised VPNs.
"Within the last few days illegal VPN ports in the country have been blocked, only legal and registered VPNs can from now on be used," Sobhani-Fard said.
Claiming it was to prevent Iran from cyber attacks the Islamic republic changed the facilities of most of its government websites from foreign-based hosting agencies to new computer locations inside the country in December 2011.
Previously, more than 30,000 Iranian websites of important organisations, such as ministries were hosted by foreign-based firms, especially in North America.
In September last year Iran barred access to Google and Gmail again highlighting cyber security, but in October it lifted a ban on the secure-protocol HTTPS version of Google search and Gmail service.
Access to YouTube has been barred since 2009.
Earlier this year, a US General said Iran had strengthened its cyber threat protection following the Stuxnet cyber attack in 2010 which hit Iranian nuclear facilities.