The protesters broke into the building of the Lebanese Ministry of Foreign Affairs in the capital Beirut, RIA Novosti reported.
They raised posters that read "Beirut - demilitarized city" and "Capital of the revolution."
The Lebanese MFA building was badly damaged in blast that shocked Beirut on Tuesday.
Thousands of people went to an anti-government rally demanding the resignation of the government and reforms. Clashes occurred between the protestors and law enforcement agencies.