The opposition said the poll was marred by rigging and voter suppression and claimed victory
Zimbabwe's main opposition on Tuesday called for fresh elections after its presidential candidate lost to incumbent Emmerson Mnangagwa in a vote it lashed as flawed and illegal.
The Citizens Coalition for Change (CCC) urged the African Union (AU) and southern Africa's regional bloc to help mediate a solution to the crisis that followed last Wednesday's vote.
"Zimbabwe needs a fresh and broad and proper election to exit the current crisis," the CCC's deputy spokesman Ostallos Siziba told a press conference in Harare.
Mnangagwa, 80, won a second term with 52.6 percent against 44 percent for the CCC's Nelson Chamisa, 45, according to official results announced late Saturday by the Zimbabwe Electoral Commission (Zec).
International observers said the vote fell short of democratic standards.
Balloting was troubled by delays, purportedly caused by the printing of ballot papers, that forced voting to spill into a second unprecedented day.
The opposition said the poll was marred by rigging and voter suppression and claimed victory.
Mnangagwa has rebuffed criticism saying the polling "demonstrated that we are a mature democracy."
He challenged those who contested his re-election to go to court.
"Those who feel the race was not run properly should know where to go to," he said.
Siziba appealed for African help in finding a way out of the crisis.
"The solution lies in calling upon our African brothers and those in the region, particularly Southern African Development Community (SADC) and the African Union, to help us to facilitate, to meditate, to scaffold and more importantly to guarantee a process that will lead our return to legitimacy," he said.
The vote has been watched across southern Africa as a test of support for Mnangagwa's Zanu-PF party, whose 43-year rule has been accompanied by a moribund economy and charges of authoritarianism.
Observer missions from the European Union, the Commonwealth and SADC listed a number of concerns, including the banning of opposition rallies, issues with the voter registration rolls, biased state media coverage and voter intimidation.
It was a rare rebuke from the 16-nation SADC whose observers usually endorse polls in the member countries.
But some member countries, including regional powerhouse South Africa, have since congratulated Mnangagwa on his re-election.
On Sunday, UN Secretary-General Antonio Guterres urged all sides to "peacefully settle any disputes through established legal and institutional channels" and resolve disputes "in a fair, expeditious, and transparent manner to ensure that the results are a true reflection of the will of the people."
The CCC did not rule out challenging the results in court, with Siziba saying the party was going to "employ all the necessary measures at the right time".