President Kais Saied on Sunday announced a declaration to abolish the Supreme Judicial Council, a move the G7 rejected as an attempt to undermine judges' independence.
Tunisia's main Western donors have voiced "deep concern" at the president's move to dissolve a body tasked with ensuring judicial independence after he seized wide powers last year in a move critics call a coup.
Ambassadors to Tunisia from the G7 group of rich democracies said "a transparent, independent and efficient judiciary and the separation of powers are essential for a functioning democracy that serves its people".
President Kais Saied announced his declaration to abolish the Supreme Judicial Council on Sunday, a move the body rejected as illegal and an attempt to undermine judges' independence.
The head of the council, Youssef Bouzakher, told Reuters news agency on Tuesday that its members were defying Saied's push to close it down and were discussing via email their next steps to oppose the move.
Tunisia faces a massive crisis in public finances, with Tunisians already complaining of shortages of some goods and with the central bank governor warning of an economic collapse like in Venezuela or Lebanon.
While Tunisia has started talks with the International Monetary Fund (IMF) for a rescue package seen as necessary to unlock other financial help, donors have urged Saied to adopt an inclusive approach to reforms.
The president has promised to uphold rights and freedoms Tunisians won in the 2011 revolution that triggered the Arab spring and brought democracy, but his latest move has increased concern for the continued rule of law.
In July he suspended the parliament and dismissed the prime minister, later saying he could rule by decree while he prepares a new constitution that he says will be put to a referendum this summer.
However, rights groups fear he is growing increasingly authoritarian and his latest move to bring the judiciary under his control would mean he had absolute power over all branches of state.
The UN High Commissioner for Human Rights Michelle Bachelet also urged Saied to restore the council, warning its dissolution "would seriously undermine the rule of law".
The judges association said in a statement that it would suspend all work in courts on Wednesday and Thursday and that judges would hold a protest against Saied's decision on Thursday.