Zimbabwe’s opposition leader Nelson Chamisa may take a mock presidential oath on Saturday, news agency Reuters quotes his spokesman as saying.
Nkululeko Sibanda said: “We will do everything that resembles an inauguration but everything will be within the law.”
Deputy Minister of Information Energy Mutodi said the government would not allow “anarchy”.
“Any attempt to de-legitimise government will not be tolerated and those bent on causing anarchy will be dealt with mercilessly,” Mr Mutodi wrote on his official Twitter page.
President Emmerson Mnangagwa won 50.7% of the vote, compared to 44.3% for Mr Chamisa in the 30 July election.
Mr Chamisa’s subsequent legal challenge was dismissed by Zimbabwe’s Constitutional Court.
However, he has maintained that he was cheated out of victory by the electoral commission.
The plan for a mock inauguration has drawn comparisons to one taken by Kenya’s opposition leader Raila Odinga in January.
He took an oath as “the people’s president” before his supporters in a park in Kenya’s capital, Nairobi, following a contentious election in 2017.
Mr Odinga and his political nemesis President Uhuru Kenyatta later called a truce and resolved to work together.