Zimbabwean President Emmerson Mnangagwa called for calm as opposition supporters, angry at alleged election fraud took to the streets of the capital Harare.
Police fired teargas and water cannons at demonstrators, mostly young men, who lit fires and threw stones at the gates of the country's vote tallying centre on Wednesday.
"I call on everyone to desist from provocative declarations and statements," Mnangagwa said on Twitter.
"We must all demonstrate patience and maturity, and act in a way that puts our people and their safety first. Now is the time for responsibility and above all, peace." Mnangagwa added.
Protests started early on Wednesday after the Zimbabwe Electoral Commission (ZEC) released results showing the ruling party, ZANU-PF, won most seats in parliament.
ZANU-PF, which has been in power since the southern African country got independence in 1980, won 145 seats in the 210-seat parliament, the commission said.
The opposition alliance, Movement for Democratic Change (MDC), picked up 60 seats.
The National Patriotic Front (NPF) won one seat while an independent candidate also picked up a seat.
Results for three constituencies in Harare are yet to be released.
With these results, ZANU-PF has won a two-thirds majority that would allow it to change the Constitution at will.
Rigging accusations
MDC and its supporters accused the ruling party of rigging the election.
"The results are a gimmick to try and prepare Zimbabwe for a rigged election. If president Chamisa wins this election then the people of Zimbabwe will have their government," Nkululeko Sibanda, an MDC alliance spokesperson said.
Outside the opposition party headquarters, MDC supporters burnt tyres and engaged police in running battles.
"I'm feeling angry at what ZEC and ZANU-PF are doing," opposition supporter Tongai Chinodya told Al Jazeera.
"They are conniving together to steal our votes. We are here to defend our vote. We are not going anywhere. The soldiers were shooting at us with live bullets. We are saying to ZANU-PF and ZEC enough is enough," Chinodya said.
The ruling party denied they rigged the election and said the vote was free and fair.
"There was no rigging and the opposition will come to realise this once emotions settle down. This was a free expression of the people's will," Nick Mangwana, ZANU-PF spokesperson said.
EU criticism
Meanwhile, observers from the European Union criticised the poll, the first vote since long-time leader Robert Mugabe stepped down in November 2017.
The EU mission said there was "un-level playing field" and "intimidation of voters".
"These elections were seen as a critical test of Zimbabwe's reform process," Elmar Brok, the EU mission's chief observer, said.
"In some senses, up to this point, the conduct of the polls has had a number of positive features, but in other senses serious concerns remain.
"Now we hope for a transparent results process." Brok added.
The presidential results are yet to be announced. The electoral body has until Saturday to release the official results.
Twenty-three candidates, 19 men and 4 women, contested for the country's top seat. All candidates were first time contenders.