Mr Carson was the first US government official to meet Mr Mugabe for years
Zimbabwe President Robert Mugabe has branded a top US envoy "an idiot" with a condescending attitude.
He said that Johnnie Carson, US assistant secretary of state for African affairs, wanted to dictate what Zimbabwe could and could not do.
The two spoke on the sidelines of last week's African Union meeting in Libya.
The Obama administration has been sceptical of the power-sharing government formed between Mr Mugabe and his opposition rivals.
Mr Mugabe told the state-owned Herald newspaper in Zimbabwe that nothing came out of his talks with Mr Carson - his first meeting with a US government official for many years.
"You would not speak to an idiot of that nature," he said. "I was very angry with him, and he thinks he could dictate to us what to do and what not to do."
Mr Mugabe pointed out that the Southern African Development Community (SADC) supported the unity government.
"We have the whole of SADC working with us, and you have the likes of little fellows like Carson, you see, wanting to say: 'You do this, you do that.'
"Who is he?
"I hope he was not speaking for Obama. I told him he was a shame, a great shame, being an African American."
Robert Mugabe met Mr Carson on the sidelines of the AU summit
Mr Mugabe was also not fond of Mr Carson's predecessor, Jendayi Frazer, who is also black.
In May last year he described her as "a little American girl trotting around the globe like a prostitute" after she suggested that the then-opposition Movement for Democratic Change had won the disputed presidential election.
Meanwhile, the Herald also reports that Zimbabwean Prime Minister Morgan Tsvangirai has apologised to Mr Mugabe after ministers from his party, the MDC, boycotted a cabinet meeting last Monday.
The ministers had decided instead to head to Harare airport to welcome Mr Tsvangirai back from a tour of Europe and the United States, where he had been lobbying for aid for Zimbabwe.
He said he had raised about $500m (£300m), not the $7bn the country's finance minister said the country needed to revive its economy.
President Obama committed $73 million, but said: "It will not be going to the government directly because we continue to be concerned about consolidating democracy, human rights, and rule of law."