"We seek to achieve democratic change through non-violent means," said Tendai Biti, secretary-general of the Movement for Democratic Change.
Zimbabwe's justice minister, Patrick Chinamasa, has accused Biti's MDC party of being "bent on foisting war" on Zimbabwe, CNN reported Tuesday.
Chinamasa, an ally of Mugabe's, said he had "compelling evidence" MDC forces were training in Botswana for an armed rebellion against Mugabe's government.
Mugabe and MDC opposition forces remain deadlocked over a power-sharing deal that has been on hold since September when Mugabe refused to cede key ministries to MDC leaders.
Meanwhile, Mugabe's government continues to reject evidence that a cholera outbreak has killed nearly 1,000 people since August and infected more than 18,400, the World Health Organization said Monday.