"Now is the time for responsibility and above all, peace".
But his threats have elicited equal warning from President Emmerson Mnangagwa who has dared his younger challenger to cause anarchy in the country.
Mnangagwa's government has accused Chamisa and his supporters of inciting "violence" by already declaring he had won.
MDC supporters took to the streets on Wednesday to protest against the outcome of the elections.
She said she was confident there was no "cheating" and that the commission will respect the will of Zimbabweans: 'We will not steal their choice of leaders, we will not subvert their will'.
The founding MDC legislator and Alliance's aspiring MP for Zengeza West, said this at a rally presided over by Alliance presidential candidate Nelson Chamisa in Chitungwiza's Chibuku Stadium Thursday.
Hundreds of Zimbabwe opposition MDC supporters gathered outside a Harare hotel where election results were being announced but police blocked the entrance to the building.
Results so far indicate Zanu-PF won 109 seats, while opposition party Movement for Democratic Change (MDC) claimed just 41, giving incumbent president Emmerson Mnangagwa a majority.More news: Fosu-Mensah hoping to stay at Manchester United
Both the European Union and US observer missions urged the release of the presidential results as soon as possible, with the lead observer for the USA team, former Liberian leader Ellen Johnson Sirleaf, warning that "the more the presidential vote is delayed, the more it calls into question the population's confidence in the election process".
The country's commission said Thursday could be the day the results are announced and that a majority of the presidential results are at its national centre.
The Zimbabwe Electoral Commission (ZEC) says vote counting and verification is at various stages and people should expect the announcement of results from around 3.pm.
"The electoral commission failed to meet the mark in a number of ways and the election failed to meet the mark in a number of ways", said Johnnie Carson, a former US assistant Secretary of State for Africa, who is part of an observer mission from the International Republican Institute and the National Democratic Institute.
Mr Mugabe had voted in the capital of Harare alongside his wife Grace, following a surprise news conference in which he called on supporters to reject ZANU-PF, his former party.
"While political rights were largely respected, there was concerns regarding the environment for the polls (and) the misuse of state resources".
But Chamisa, a lawyer and pastor who performed strongly on the campaign trail, sought to tap into the youth and urban vote.
Sikhala warned of dire consequences if Zanu PF tries to deny the opposition its victory.