The UGTT trade union federation, which mediates between Ennahda and critics, proposed the government step down and let a neutral interim cabinet prepare new elections.
Islamist Ennahda party chairman Rached Ghannouchi said he hoped the negotiations would resolve the standoff that has paralysed Tunisian politics for almost a month.
"We will get out of this crisis very soon," he told journalists after meeting UGTT secretary general Hussein Abassi.
"We accept the UGTT initiative in principle to begin the dialogue with the opposition."
The country has seen mass protests and calls for the government to resign.
Ennahda is in coalition with two smaller secular parties, but is under pressure over accusations of an Islamist agenda, failure to stop violent Salafi radicals and mismanagement of the economy.