Tunisia is seeking a deal on a $4 billion loan from the IMF in return for unpopular reform.
The government reform package included a wage freeze and cuts in food and energy subsidies.
One of Tunisia’s main political parties, the Constitutional Free Party, said it would not recognise any agreement that Tunis makes with international lenders.
The Constitutional Free Party, which polls say would win by a large margin over rivals in any parliamentary elections, joined UGTT union in rejecting economic reforms demanded by the IMF.
The powerful UGTT union, with one million members, went on strike on Thursday and brought much of Tunisia to a standstill, over the government’s economic reform plans, increasing pressure on President Kais Saied.
After a decade of the revolution that brought democracy, Moussi’s party has become the main player in Tunisia as popular frustration grows with economic stagnation.
On Saturday, thousands of the party’s supporters protested against President Saied.