"This government will stay in office," Tunisian Prime Minister Ali Larayedh told state television on Monday. (Agencies)
"We are not clinging to power, but we have a duty and a responsibility that we will exercise to the end," he added, proposing December 17 for a general election.
An official declaration of mourning came after the discovery on Monday of soldiers' bodies in the Mount Chaambi area, near the border with Algeria. Troops there have been hunting Al-Qaeda-linked fighters.
While the official Defence Ministry toll was eight dead, medical and military sources had earlier said that nine soldiers had been killed. Some of them had had their throats cut, the sources added. State television ran pictures of the mutilated corpses of the victims.
In a televised address, President Moncef Marzouki, a secular politician allied to the ruling moderate Islamic Ennahda party, called for national unity after the soldiers' deaths.
"If we want to face up to this danger we have to face up to it united," he said.
"I call on the political class to return to dialogue because the country, society, is under threat," he added.
Marzouki also referred to last Thursday's assassination of the senior opposition politician Mohamed Brahmi, the event that triggered the latest series of anti-government protests.
The government has blamed his murder on Islamist extremists and Marzouki regretted that this "tragedy" had divided the country rather than uniting it.
But the government's critics say that the Ennahda-led cabinet has failed to rein in radical Islamists who have grown in influence and stand accused of a wave of attacks since the 2011 uprising.
Since Brahmi's death, around 60 politicians have pulled out of the work of the National Constituent Assembly (NCA) that is drawing up the country's new constitution.
NCA speaker Mustapha Ben Jaafar has called for "restraint" and urged deputies to return and resume work on the much-delayed constitution, one of the thorniest issues in post-revolution Tunisia.
"This government will stay in office," Tunisian Prime Minister Ali Larayedh told state television on Monday.