The speaker of the assembly said work on a new constitution and electoral law would resume once "dialogue commences".
There have been daily protests calling for the body to be dissolved since one of its members was assassinated.
Mohamed Brahmi was shot on 25 July, almost six months after fellow leftist politician Chokri Belaid was killed.
About 60 members of the National Constituent Assembly (ANC) withdrew in protest at the killings and organised a sit-in outside its headquarters in the capital, Tunis.
Later on Tuesday, tens of thousands of people participated in a protest in central Tunis called by the opposition to demand the assembly's dissolution and the government to resign, and to mark the six-month anniversary of the assassination of Chokri Belaid.
The powerful Tunisian General Labour Union (UGTT) called on its 600,000 members to join the rally.
On Tuesday morning, the ANC was convened despite the absences. An empty chair where Mr Brahmi used to sit was draped in a Tunisian flag and covered in flowers and a picture of him.
Prime Minister Ali Larayedh urged the assembly to "hurry and finish the constitution quickly" so that fresh elections could be held in December. The body has already gone eight months beyond its promised deadline.
However, on Tuesday evening ANC Speaker Mustapha Ben Jaafar announced on television that it would "suspend its work until dialogue commences, in the service of Tunisia".
Mr Ben Jaafar, whose Ettakatol party is part of the cabinet, condemned the failure of politicians to resolve the political crisis.
"Despite the gravity of the situation and instead of working towards unity, party leaders have unfortunately gone in the opposite direction - towards division," he said. "The people are fed up with this situation and can no longer tolerate this wait."
Mr Larayedh has refused to step down and appealed for "national unity".
The political unrest is the worst seen in Tunisia since President Zine al-Abidine Ben Ali was overthrown by a popular uprising in January 2011.
In a separate development on Tuesday, police shot dead an Islamist militant in the Tunis suburb of Rawad, interior ministry officials said.
Tunisia's constituent assembly has been suspended until the Islamist-led government and secular opposition begin talks to resolve a political crisis.