The MDC, led by Prime Minister Morgan Tsvangirai, backed by South African mediators, insists that a new constitution is in place before the new polls to ensure they are free and fair.
President Mugabe, who has been in power since independence in 1980, denies accusations that previous elections were rigged in his favour.
Mr Tsvangirai pulled out of the previous election, in 2008, citing systematic attacks on his supporters by the army and pro-Mugabe militias.
With the uncertainty pushing Zimbabwe's economy into freefall, the pair then agreed to form a power-sharing government.
Mr Mugabe's proposed election timetable was included in court papers in a case about when to hold by-elections.
The Supreme Court had ordered that by-elections for several vacant parliamentary seats be held by 1 October. However the president has appealed against the ruling, saying it would cost too much money when wider elections are expected soon.
This is by no means a fixed date for Zimbabwe's long-awaited elections, but it is a sign of growing urgency, according to the BBC.
But it was immediately rejected by MDC spokesman Douglas Mwonzora.
"The date for the election, especially, is unilateral, unrealistic and has no scientific or legal basis," he told the AFP news agency.
Mr Mugabe and Mr Tsvangirai would be expected to face each other in the poll, which is supposed to be held by next year.