HARARE - Zimbabwe Citizens Coalition for Change is calling for fresh elections.
The main opposition's presidential candidate Nelson Chamisa lost to incumbent Emmerson Mnangagwa in last Wednesday's vote.
The CCC has blasted the poll as both flawed and illegal
The party has urged both the African Union and SADC to help mediate a solution to the crisis.
Mnangagwa won a second term with 52.6-percent against 44-percent for Chamisa, according to official results announced by the Zimbabwe Electoral Commission.
International observers said the vote fell short of democratic standards.
READ: Zimbabwe Elections | CCC launch a citizens' review of elections
Mnangagwa has rebuffed criticism saying the polling demonstrated that Zimbabwe is a mature democracy.
He challenged those who contested his re-election to go to court.
CCC deputy spokesperson Ostallos Siziba said, "it is clear, it is non-negotiable that we cannot settle for any leader in Zimbabwe who lacks the true democratic will of the Zimbabwean people."
"A leader must be born out of a legitimate electoral process because that is what democracy and election is all about." "The solution lies in calling upon our African brothers and those in the region, particularly SADC the African Union, to help us to facilitate, to mediate, to scaffold and more importantly to guarantee a process that will lead our return to legitimacy."