Opposition supporters had marched to and from the gates of a compound where the Zimbabwe Electoral Commission had been announcing results.
He added: "The strategy is meant to prepare [Zimbabwe] mentally to accept fake presidential results".
United Nations deputy spokesman Farhan Haq appealed to Zimbabwe "to exercise restraint and reject any form of violence while awaiting resolution of the disputes and announcement of the election results".
The party faithful had gathered at MDC headquarters in the early morning and sung, chanted and held their hands high in a collective act of protest.
"We have the necessary legal power and enough personnel to deal with unruly elements in our society and if people want to test our patience‚ then they will be very disappointed; very disappointed‚" he said.
The MDC opposition party condemned the army for opening fire on protesters "for no apparent reason".
The electoral commission had said it would start announcing results for the presidential race from 12.30pm but election officials said they would announce the results from Thursday.
Tendai Biti, a candidate for opposition party Movement for Democratic Change (MDC), has accused the ruling Zanu-PF regime of plotting to assassinate himself and Chamisa.
The deployment of soldiers and clashes with protesters set back President Emmerson Mnangagwa's efforts to shed Zimbabwe's pariah status after decades of repression under Robert Mugabe, who was ousted in a coup in November.
The opposition alleges the elections have irregularities, saying voting results were not posted outside one-fifth of polling stations as required by law.
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The House of Assembly of Parliament has 210 seats and ZANU-PF's two-thirds majority would allow it to change the constitution at will.
This follows violence which erupted yesterday at the Harare International Convention Centre, where thousands of members from the opposition demonstrated to the Elections Command Centre as counting of the results was under way.
"The longer it lasts that the results of the presidential election is not known, the more lack of credibility it provides", he said.
The Zimbabwe Electoral Commission by law has until Saturday to release the final election tally. MDC leader Chamisa has said outright that his own count shows he won the election, drawing government accusations of inciting violence.
Police patrol outside the Zimbabwe Electoral Commission offices in Harare, Zimbabwe.
The ZANU-PF leader tweeted: "At this crucial time, I call on everyone to desist from provocative declarations and statements".
If no presidential candidate wins at least 50 percent of the ballots cast in the first round, a run-off vote is scheduled for September 8.
"You can't rig our election.this is a military government", the crowd shouted. Another opposition party, National Patriot Front (NPF) won 1 and an independent candidate also took one.
Ruhanya said: "It seems the results so far could indicate the will of the people, especially the rural population, to be ruled by ZANU-PF".
It alleges that the governing Zanu-PF party has rigged Monday's elections.