South Africa is trying to avoid Zimbabwe becoming a "failed state", its deputy foreign minister has said.
Some 700,000 people have lost their homes or their livelihoods this year, the UN says
Aziz Pahad said South Africa did not want Zimbabwe's government and opposition to form a government of national unity to solve its problems.
He said South Africa wanted Zimbabwe to change its economic policies, in return for a loan, which is being negotiated.
Meanwhile, Zimbabwe's government has again ruled out the idea of holding talks with the main opposition party.
Zimbabwe is going through an economic crisis, with shortages of food, fuel and foreign currency, and rampant unemployment and inflation.
It has asked South Africa for an emergency loan so it can repay its debts to the IMF and avoid expulsion.
There had been reports that South Africa was insisting the government hold talks with the opposition Movement for Democratic Change (MDC), or even that they form a coalition government.
"We are negotiating in the... broad context that we need fundamental economic changes, and how do we minimise the political tensions of Zimbabwe without necessarily talking about governments of national unity," Mr Pahad said.
He said the conditions of the loan had not been finalised.
Zimbabwe's President Robert Mugabe has denied responsibility for the economic problems - blaming them on a Western plot to remove him from power.
The South African government has been criticised at home and abroad for not taking a tougher line with Mr Mugabe over alleged human rights and electoral fraud.
But Mr Pahad defended South Africa's policy of "quiet diplomacy".
"All our interventions on the Zimbabwean issue have been to prevent a failed state on our doorstep," he said.
Meanwhile, Zimbabwe's acting information minister has dismissed the appointment of an African Union envoy for Zimbabwe.
Chen Chimutengwende said there was no point in naming former Mozambique President Joaquim Chissano, according to the state-owned Herald newspaper.
"This is because there will be no talks between Zanu-PF and the MDC," he said.
Southern African leaders are meeting in Botswana this week but Mr Mugabe's officials have denied reports that they would be discussing Zimbabwe's problems.