"What we know and what we believe is that a basis for a free and fair contest is ... that there should be negotiations and those negotiations should lead to all parties accepting that the conditions are free and fair. Without that, it will be a unilateral position by Mugabe and not by us."
Tsvangirai's spokesman said that many sectors of the public hold similar views, and may boycott the elections.
William Bango said: "It's not only Morgan Tsvangirai or the MDC who are saying they will boycott the elections if certain conditions are not met.
"It's the people of Zimbabwe who are saying they have no confidence in the current conditions and will not partake in an activity whose result will not reflect a correct record of their voice."
Ready for polls
Tsvangirai, who has accused Mugabe of rigging past elections, said that if the deadlock could be overcome, the opposition was ready to face Mugabe at the polls and that the fractured opposition would field a single candidate for each contested seat.
The MDC has been severely weakened by infighting which resulted in a sharp split in October 2005 and a crackdown by the government that has paralysed its structures.
The president denies rigging past elections and says the MDC has lost the support of voters.
Mugabe, 83, who has been in power since the nation gained independence in 1980, is seeking a sixth term of office.