In Tebourba, where a man died during unrest overnight Monday-Tuesday, police fired tear gas at dozens of protesters, a resident said.
The military has been deployed to protect government buildings, banks and stores, the defense ministry said.
Protests are hardly new: In November, a mother of five killed herself by setting herself on fire in the town of Sejnane to protest her desperate economic plight.
The current protests are being driven by economic considerations related to a new budget law. He claims it only benefits the corrupt and those who want to weaken the state.
"They pretend they are fighting corruption but it's the opposite, they are covering it up". He said that many public buildings have been targetted while the government has "taken a pretty strong stance against the protesters".
Worldwide lenders extended a crucial $2.8bn (£2.1bn) loan to Tunisia a year ago, but have demanded cuts to the civil service and a broader austerity programme.
"I'm not feeling a lot of hope, but we are saying no [to austerity]", said Mhamdi. Unemployment meanwhile stands at over 15 percent, with more than a third of all younger workers without jobs. "I can not afford to marry". "With 500 dinars a month" - about $200 - "you can't survive anymore, and our salaries don't go beyond 400 dinars", he said.
More than 600 people have been arrested this week for their part in the unrest.
Tunisian police have arrested over 325 people after four nights of anti-austerity protests, according to the Interior Ministry spokesman, Khelifa Chibani. Sixteen "Islamist extremists" were among those detained, he said. He called upon all political parties to unite around a policy aimed at "putting an end to people's anger". Wednesday was the third successive night of violence, with nearly 600 people arrested in total since the start of the week.
Hamma Hammami, leader of Tunisia's Popular Front Party and presidential candidate, speaks during a campaign event in the capital Tunis November 16, 2014.
The protests draw on anger over price and tax increases included in this year's budget that took effect on January 1.
The government has blamed the opposition and "troublemakers" for stoking unrest, a charge the opposition has denied.
Anger has been building up since the government said that, from January 1, it would increase the price of gasoil, some goods, and taxes on cars, phone calls, the internet, hotel accommodation and other items, part of austerity measures agreed with foreign lenders. Gasoline prices, retirement plan contributions, and taxes on "cars, phone calls, internet usage and hotel accommodation" have all gone up, Reuters says.
A student in Sousse, Mouna Ali, told Al Jazeera that the government's austerity measures represented "a catastrophe for the middle class", adding, "The Tunisian government needs to understand that Tunisian society is fed up".