Mass protests forced out veteran President Zine al-Abidine Ben Ali last month
Security forces in the Tunisian capital have fired tear gas to try to disperse hundreds of demonstrators outside the Interior Ministry, reports the BBC.
Police and masked men in civilian clothes, armed with sticks, moved through streets looking for protesters.
The renewed protest comes a day after police cleared huge crowds from the streets demanding the resignation of the interim Prime Minister.
That was the biggest rally since the president fled after weeks of unrest.
On Friday police fired tear gas and warning shots to disperse demonstrators.
The BBC's Paul Moss in Tunis says the stench of tear gas is again filling the main shopping street in Tunis.
The trouble flared very suddenly - people out shopping found themselves caught up in the confrontation, women carrying heavy bags running for cover with handkerchiefs clutched to their mouths, our correspondent says.
Several members of the security forces ran into the lobby of a hotel, yelling at startled customers drinking coffee to return to their rooms or leave the hotel immediately, he said.
The interim government of Mohammed Ghannouchi, who had served under ousted President Zine al-Abidine Ben Ali since 1999, has promised elections by mid-July.
Although Ghannouchi has introduced some reforms and removed a number of controversial cabinet members, protesters remain angry that figures from Ben Ali's authoritarian government remain in the interim cabinet.