But ZANU-PF denied the Opposition's accusations of manipulating the vote even as hundreds gathered in the streets of Harare to protest the results.
The historic elections were the first without former President Robert Mugabe at the helm and, less than a year after he was forced to resign in the wake of a military takeover. Police have been blamed for using live bullets on opposition protesters.
The 40-year-old lawyer and pastor tweeted: "Zec seeks to release results to buy time & reverse the people's presidential election victory".
The United States Embassy in Harare is deeply concerned by events unfolding in Harare.
Police block dozens of opposition party supporters from entering the Zimbabwe Electoral Commission offices in Harare, Zimbabwe, Wednesday, Aug. 1, 2018.
"I wasn't sure whether it's safe to come to work". One independent candidate and a member from a party linked to Mugabe also won one seat each.
Elsewhere markets were open and queues formed outside banks - a common sight in Zimbabwe due to the country's chronic shortage of banknotes.
"People must be guaranteed their right to protest", he said.
Mnangagwa previously said the opposition was to blame for the violence, though some worldwide observers criticized the military for opening fire on unarmed civilians.
The violence erupted after the Zimbabwe Electoral Commission said the ruling ZANU-PF party won a majority in parliament.More news: GOP House Members Move To Impeach Deputy Attorney General Rod Rosenstein
Biti was finance minister in the 2009 to 2013 government, which saw Zanu-PF and opposition parties under the MDC alliance share power, and is said to be a respected politician in Zimbabwe.
He has already declared he's won the popular vote and the Zimbabwe Electoral Commission is preparing the country to accept "fake presidential results".
But the mission welcomed an "improved political climate" and largely peaceful election, a break from past violence under longtime autocratic leader Robert Mugabe.
But the mood quickly descended into anger as MDC supporters rallied in the city, chanting against the government and burning tyres in the streets.
Observers had raised concerns about the independence of the electoral commission ahead of the vote, pointing to close ties to the ruling party and the military.
The EU observer mission said "a truly level playing field was not achieved" in the election, pointing out the "misuse of state resources, instances of coercion and intimidation, partisan behaviour by traditional leaders and overt bias in state media". It called for transparency in the release of results. "Call on Zimbabwe's political leaders to take responsibility for ensuring calm & restraint at this critical moment".
Under Mugabe, elections were often marred by fraud and deadly violence.
At the press briefing, Zec also announced the last of the House of Assembly results, and the MDC Alliance's Elizabeth Java Tsvangirai and Susan Matsunga won the Glen View South and Mufakose constituencies respectively. We've more votes than ED (Emmerson Mnangagwa). He said he did not understand why the election commission was taking so long to release results and that it would lose credibility with further delays.
Well, the country will be waiting to see what the ZEC Chairperson, Mr Priscilla Chigumba will be announcing in a couple of days.