Justice minister Ziyambi Ziyambi announced a ceremony planned for Sunday “will no longer happen” after the Movement for Democratic Change (MDC) alleged irregularities in the country’s first vote since long-serving leader Robert Mugabe was deposed.
The opposition party has demanded either fresh elections or the instalment of their candidate, Nelson Chamisa, as president.
The MDC’s lawyers arrived at court to submit papers less than an hour for the deadline to challenge the result.
“We have a good case and cause,” declared Mr Chamisa on Twitter.
Zimbabwe’s Electoral Commission has said President Mnangagwa and his ruling Zanu-PF party won the 30 July election, with the president receiving 50.8 per cent of the vote and Mr Chamisa polling 44.3 per cent.
The vote was Zimbabwe’s first without Mr Mugabe on the ballot, after a coup in November ended his 30-year rule as president.
There had been hopes the end of Mr Mugabe’s presidency would begin a new era for the country, which has long been an international pariah beset by economic crisis.
But Zimbabwe has been rocked by violence since following the bitterly disputed election.