An MDC spokesman responded by throwing the charge of reposnsibility for the violence back at the president.
"He is the one who has gone about threatening to go back to war if he loses," Nelson Chamisa said. "So while he is accusing us of violence, he is responsible."
Though Mugabe blames the opposition for the upsurge in violence, the UN has said the president's supporters are to blame for the bulk of it.
The MDC says more than 60 of its supporters have been killed in a campaign of intimidation since the first-round election on March 29.
Tsvangirai won the first round presidential poll but did not win enough votes for an outright victory, forcing the run-off.
Also on Monday, the secretary-general of the MDC - the party's number 2 - continued to be held in the notoriously harsh police jail in western Harare, his lawyer said.
Tendai Biti did not make a scheduled appearance in court on Monday on treason allegations.
Biti had yet to be asked by police to make a formal written "warned and cautioned" statement, needed before he can be arraigned, lawyer Lewis Uriri.
Uriri said if Biti was not brought to court, the case would be taken to the high court again to request it to order an end to delays that are keeping Biti in the Matapi police jail in the western township of Mbare.
Also on Monday, one of the UN's senior officials arrived in Zimbabwe on a fact-finding mission.
Haile Menkerios, the UN Assistant Secretary General for Political Affairs, said he would report back to Ban Ki-Moon, the UN Secretary General, after his visit.