"Mr. Obama's behaviour and the positions he has taken show that he is still a prisoner in the hands of extremist Republicans and is unable to wipe out the policies of (former president George W.) Bush from the White House," Ali Akbar Javanfekr, Ahmadinejad's media advisor, was quoted as saying by ISNA news agency.
"The interfering stance of the US after the Iranian election and his refusal to congratulate the president of Iran on his victory overtly show that Obama is unable to adopt a new approach towards the Islamic republic and is being forced to take the path of the Republicans."
Javanfekr also said that Ahmadinejad would not be holding talks with US officials during his visit to the UN General Assembly meeting later this month.
Ahmadinejad at a Tehran press conference a week ago had reiterated that he was ready to hold a debate with Obama to discuss global issues.
Javanfekr said American officials had not replied to the suggestion, which, he said, had made them "agitated."
"The debate is one way of solving international issues, but it seems that this suggestion has made Americans agitated because so far we have not witnessed any positive feedback from the American president in this regard," he said.
Officials in Washington have said that Ahmadinejad should not expect to be invited to a leaders reception Obama will host at the UN General Assembly.
White House spokesman Robert Gibbs said the reason was that, "Iran is failing to live up to its international obligations."
Iran and the US have had no diplomatic relations since the 1979 Islamic revolution.
Washington and five other world powers are seeking an urgent meeting with Tehran to resolve a row over its controversial nuclear programme.
Iranian officials, including supreme leader Ayatollah Ali Khamenei, have refused to climb down on the atomic programme.
