Reacting to the US move, al-Manar said its right to freedom of expression was being infringed.
"Acting under the authority of ... the Immigration and Nationality Act ... and in consultation with the Attorney General and the Secretary of Homeland Security, the Secretary of State has concluded that al-Manar is a 'terrorist organisation' within the meaning of that section of the INA," the notice said on Friday.
The designation is effective upon Friday's publication.
The United States has already designated Hizb Allah as a "foreign terrorist" organisation, and the state department has been open in its criticism of al-Manar's satellite television programmes.
"We consider (al-Manar) to be disgusting programming that preaches hatred and violence and ... ideas that are antithetical to the values which we believe in," department spokesman Adam Ereli said at a briefing on 9 December.
Al-Manar says its freedom of
expression is being infringed
On Monday, a French court ordered the French-based Eutelsat company to shut down al-Manar broadcasts following accusations that its programmes were anti-Semitic and could incite hatred.
Al-Manar says the French decision was political and not legal, influenced by Israel and Jewish lobbies. It plans to pursue its case to restart using the French platform. The ruling has been widely condemned in Lebanon.
A designation by the state department may only be the first step against al-Manar.
The Treasury could decide to include al-Manar on its terrorism blacklist, blocking its assets and making any financial dealings with the channel illegal.