A heavy police presence prevented the protesters gathering in Habib Bourguiba Avenue, the main street in central Tunis that is the traditional focal point of demonstrations including during the 2011 revolution that brought democracy.
Police then tried to disperse several different groups of protesters, at least one of which had hundreds of demonstrators, witnesses said.
Opposition parties including the moderate Islamist Ennahda are protesting against President Kais Saied's suspension of parliament, assumption of executive power and moves to rewrite the constitution, which they call a coup.
"Today, January 14th, is the anniversary of the Tunisian revolution and preventing free Tunisians from protesting is a terrible regression," Imed Khamiri, the head of the Ennahda party in parliament said.
Dozens of police cars stood in the area and two water cannon were placed outside the Interior Ministry building, which is located on the same street.
Friday's protest goes against a ban on all indoor or outdoor gatherings the government announced on Tuesday to stop a COVID-19 wave.