"But as we know, the regime is trying to make the situation on the ground so terrible that they hope the run-off election - an election they will lose - will be cancelled."
He said that it was "not the decision of the regime or the international community to silence the people of Zimbabwe".
The South African teamm, which arrived in Zimbabwe late on Friday, includes Sydney Mufamadi, the local government minister, and Mojanku Gumbi, a presidential adviser, Mukoni Ratshitanga, Mbeki's spokesman, said.
Ratshitanga refused to comment on reports that Mbeki was seeking to have the election abandoned as well as any further details of the mediation.
The 14-nation Southern African Development Community (SADC) appointed Mbeki as a mediator between President Robert Mugabe and Tsvangirai, travelling to Zimbabwe earlier this week to meet both parties.
"He [Mbeki] has warned that the run-off might exacerbate the situation," South Africa's Star newspaper quoted an unnamed official as saying.
According to the newspaper, Tsvangirai told Mbeki that he was prepared to meet the Zimbabwean president, but Mugabe was resistant to talks with his opponent.
Simba Makoni, Zimbabwe's ex-finance minister and a candidate in the first round of the poll, urged for the election to be scrapped and a transitional government to be formed.
Makoni, who split from Mugabe's Zanu-PF party to run as an independent, has said violence has made a fair vote impossible.
The opposition claims that about 70 of its supporters have been killed in a campaign of intimidation since the first round in March.
The 84-year-old leader has remained defiant in the face of criticism over conditions before the vote, dismissing the opposition claims as a ploy aimed at casting the election as unfair.
"They have been saying their supporters are being beaten up by our soldiers," the Herald newspaper quoted Mugabe as telling an election rally in the second city Bulawayo on Friday.
"They say this so that they can later say the elections were not free and fair ... Which is a damn lie."
Mugabe has threatened to arrest opposition leaders over the violence, despite the UN saying that his supporters were to blame for much of it.