"Political associations are prohibited from having any form of contact with the Hezbollah organisation," Justice Minister Sheikh Khaled bin Ali Al-Khalifa said in a ministerial decree.
A second clause in the same decree stated that the Iran- and Syria-backed group is a "terrorist organisation."
The decision appears aimed at opposition groups, which are mostly Shiites, who dominated anti-regime protests that erupted in February 2011 before coming under a brutal crackdown a month later.
"Terrorist Nasrallah has declared war on his nation," Sheikh Khaled wrote on his Twitter account.
"Stopping him and rescuing Lebanon from his grip is a national and religious duty for all of us," he said, as Hezbollah's involvement in Syria's armed conflict deepened.
Last month the decided to list Hezbollah as a "terrorist organisation", following a recommendation by the parliament that is boycotted by the opposition.
Despite the March 2011 crackdown on protests, Shiites continue to demonstrate in their villages, triggering frequent clashes with police.
A total of 80 people have been killed since the protests erupted, according to the International Federation for Human Rights.
