Religious leaders that hosted a highly-criticised dinner for Iranian President Mahmoud Ahmadinejad on Thursday asked the fiercely anti-US politician to change his tone when speaking on a number of sensitive topics.

Arli Klassen, executive director of the Mennonite Central Committee, introduced the discussion by maintaining that dialogue is crucial when people hold conflicting views. But she also pressed the hardline Iranian leader to change the way he speaks, which has made him many enemies worldwide.

"We are deeply concerned when your statements about the Holocaust minimise or diminish its impact on our world today," said Klassen to Ahmadinejad, according to Reuters, "and on Jewish people today.

"We ask you to change the way you speak about the Holocaust," she challenged.

She also asked the controversial guest to avoid rhetoric that "is heard as a threat to destroy the state of Israel", to respect religious freedom in Iran, and to be more transparent about the country's nuclear programme.

In the past, Ahmadinejad has stated that Israel should be wiped off the map. He has also convened a highly-controversial conference in 2006 to question the historical truth of the Holocaust.

Rabbi Lynn Gottlieb, who was also a speaker, admitted that "a lot of it was very challenging" concerning Ahmadinejad's speech. While the Iranian president did not outright deny the Holocaust, she noted, he had minimised it in how he spoke about World War II.

"Our world views are rather different. But unless we ... dialogue face to face, how will we create any kind of understanding?" Gottlieb said, adding that she chose to attend because "peace is better than war".

Some 200 people of various faiths, including Mennonites, United Methodists, Jews and Zoroastrians, attended the dinner in New York City - an event meant to promote peace between the two countries.

But outside the Manhattan hotel near the United Nations headquarters were protesters who brandished signs that read "No feast with the beast" and compared Ahmadinejad to Hitler.

Likewise, religious and human rights groups such as the US Commission on International Religious Freedom, the American Center for Law & Justice, and Institute on Religion and Public Policy have condemned the dinner event for seemingly honouring or welcoming the figure who has been linked to terrorism and horrendous human rights violations.