The MDC statement came shortly after a spokesman for Mugabe's Zanu-PF also dismissed any suggestion of talks towards power sharing.
Mugabe was sworn in as Zimbabwe's president on Sunday after standing as a lone candidate in an election boycotted by the MDC.
Morgan Tsvangirai, the MDC’s leader, pulled out of the vote last week, citing a campaign of violence and initimidation against his supporters by members of Mugabe’s Zanu-PF.
The two sides' rejection of negotiations talks came as AU leaders in the Red Sea resort of Sharm el-Sheikh began debating a resolution that would call for a national unity government in Zimbabwe.
"Kenya is Kenya. Zimbabwe is Zimbabwe. We have our own history of evolving dialogue and resolving political impasses the Zimbabwean way. The Zimbabwean way, not the Kenyan"
George Charamba, spokesman for Robert Mugabe
Sources at the summit said the resolution would call for talks between Mugabe's government and the opposition, while pledging AU support for the
However, Botswana called on Tuesday for Zimbabwe to be suspended from meetings of the AU and Southern African Development Community (SADC) due to Mugabe's controversial re-election.
The AU's moves towards a resolution come a day after most political leaders at the summit refrained from criticising Mugabe, despite Western demands they take a tough stance over his re-election.
Some African leaders, including Raila Odinga, Kenya's prime minister, have pushed for Mugabe to share power with Tsvangirai.
However, George Charamba, a Mugabe spokesman, on Tuesday dismissed calls for a Kenya-style grand coalition government.
"Kenya is Kenya. Zimbabwe is Zimbabwe. We have our own history of evolving dialogue and resolving political impasses the Zimbabwean way," Charamba said at the AU summit.
"The Zimbabwean way, not the Kenyan way. Not at all."
As leaders from the 53-member AU held closed-door talks in Sharm el-Sheikh on how to deal with the situation in Zimbabwe, the US prepared UN sanctions in response to Mugabe's re-election.
Meanwhile, Ban Ki-moon, the UN secretary-general, has pledged to work to resolve the political crisis in Zimbabwe and repeated his view that Mugabe's re-election lacked legitimacy.
Zimbabweans should be able to "enjoy genuine freedom" so they can "choose their leaders out of their own will without being intimidated", Ban said in Tokyo on Tuesday.
"You have my full commitment that I will spare no efforts to work out a solution," he said.
|Morgan Tsvangirai says Mugabe's
re-election is a "sham" [AFP]
Many African countries, including regional power South Africa, have been unwilling to condemn Mugabe's re-election but there has been mounting criticism from the US and Europe.
During public speeches at the summit on Monday, most AU leaders did not criticise Mugabe but spoke of the "challenges" in Zimbabwe and focused on other issues facing Africa.
But Jendayi Frazer, the US secretary of state for African affairs, said she believed that, in private, leaders at the summit would "have very, very strong words for him".
"I would suggest that one not take from the soft words in an open plenary as a reflection of the deep concern of leaders here of the situation in Zimbabwe," she said.
A White House spokesperson also suggested that Mugabe is facing pressure from behind the scenes.
Dana Perino said Mugabe's actions have "cast a negative light on some really good, democratic leaders in Africa.".
"There are a lot of them who are working very hard to institute democratic reforms in their own way," she said.