Ahmadinejad, speaking at a rally in Yasouj, said Iran wouldn't allow anybody to compromise what he called the country's inalienable nuclear right, Press TV reported.

U.S. Undersecretary of State William Burns attended a weekend meeting in Geneva, during which Iran responded to a U.N. proposal to suspend Tehran's nuclear program. Iran didn't give a yes-or-no response, prompting Western leaders to give the country two weeks to respond positively or face economic sanctions as early as late August, the Los Angeles Times reported.

Ahmadinejad said Burns' presence at the talks was "positive."

"The U.S. administration announced it was going to participate in nuclear talks. We welcomed that. The U.S. representative spoke in a gentlemanly tone in the meeting. It was positive," Press TV quoted the Iranian leader as saying.

But he warned the United States not to undermine the step by making more "baseless allegations" about Iran's intentions, the broadcaster said.