The Tunisian government has issued a statement condemning the "extremist groups" that have rioted across the country over the last few days, and the artists whose provocative works partly inspired the riots.
The rioting left one man dead, injured 62 security personnel and led to more than 160 arrests.
The joint statement was signed by Moncef Marzouki, the president, Mustapha Ben Jaafar, the head of the constituent assembly, and Hamada Jebali, the prime minister.
It warned against "plans by provocateurs and extremists to perturb authority and sow terror".
"Extremist groups are threatening freedoms, claim the right to substitute themselves for state institutions and try to bring places of worship under their control," the statement said.
"These groups are infiltrated by criminals ... the ghosts of the ousted regime are trying to block the process of transition."
But the three men also said that "attacks on religion do not stem from freedom of expression, [but] aim to provoke and sow discord as well as take advantage of a sensitive situation to stoke tension."
The government on Tuesday imposed a dusk-to-dawn curfew in eight areas of the country, including the capital, in a bid to stem the violence, much of which targeted courts and other state buildings.
Police in the capital Tunis had fired tear gas on Monday night to disperse protesters who torched a local courthouse and attacked several police stations.
Protesters blocked streets and set tyres alight in the working class Ettadamen and Sidi Hussein districts, hurling petrol bombs at police in some of the worst confrontations the city has seen since last year's revolution.
There was evidence of looting in some areas, where shop windows were smashed.
A day earlier, a group of Salafis, who follow a strictly conservative interpretation of Islam, forced their way into an art exhibition in the upscale La Marsa suburb and defaced works they deemed offensive.
The interior ministry vowed to punish the perpetrators.
Salafis denied involvement in the rampages and instead called a protest after this week's Friday prayers.
The artwork that appears to have caused the most fury and polarised Tunisians spelt out the name of God using insects.
Othmane Batikh, the mufti of Tunisia, called on the constituent assembly to pass laws against blasphemy.
"The sacred symbols of Islam are red lines that must not be crossed," he said.
It was the latest incident in a series of confrontations between Salafis and more secular state and civil institutions, including universities, which have flared over the past year in Tunisia.
In a statement released before the protests, Ennahda, the moderate Islamist party that now leads the government, condemned what it described as provocations and insults against religion but urged its own supporters to respond peacefully.