Clashes between police and young protesters erupted for a second night in Kairouan after the death of a man during a police chase, raising fears of wider unrest.
The man, who was riding a motorcycle without a license, was chased by police, beaten and hospitalized, his family said. He later fled but died Friday from head injuries.
On Saturday, protesters burned tires and hurled stones, Molotov cocktails and flares at security forces, who responded with tear gas, eyewitnesses said.
The governor of Kairouan visited the family and pledged an investigation.
The unrest comes as Tunisia nears the anniversary of the 2011 revolution. The UGTT union has called for a nationwide strike in early January.
In Gabes, thousands have staged protests for weeks demanding closure of a chemical plant over environmental concerns.