"I think we have sufficiently talked about this matter and these Holocaust events need to be further investigated by independent and impartial parties," Mahmoud Ahmadinejad said at a news conference on Friday following a meeting with China's president.
"An event that has influenced so many diplomatic and political equations of the world needs to investigated and researched by impartial and independent groups," he said.
Speaking in Shanghai, China, he added that Jews, Christians and Muslims all had the "right to be respected."
Ahmadinejad has come in for sharp criticism in Europe for repeatedly casting doubt on the Holocaust and calling for Israel to be destroyed or shifted to Europe.
On Monday, German Jews and politicians protested Iranian President Mahmoud Ahmadinejad's repeated denial of the Holocaust while his country kicked off its World Cup campaign on Sunday, declaring that he would be unwelcome at the tournament.
About 1,200 people, according to police estimates, gathered in a downtown Nuremberg square, many waving Israeli flags.
In the end of May, during a Spiegel interview, Ahmadinejad was quoted as saying that he doubted the magazine would write 'the truth' about the Nazi genocide against Europe's Jews.
'We want to know whether this crime really happened or not. If so, then those responsible should be punished and not the Palestinians ... If it didn't happen, then the Jews have to go back where they came from,' he was quoted as saying.
He also played up the credentials of Western Holocaust deniers such as the British historian David Irving and echoed some of their views.
AP contributed to this report.