WASHINGTON (Reuters) - Iranian President Hassan Rouhani denounced ISIS beheading of innocent people, saying the militant group's shameful actions violate Islamic principles, NBC News said in excerpts of an interview released on Wednesday.

"From the viewpoint of the Islamic tenets and culture, killing an innocent people equals the killing of the whole humanity," Rouhani told the television network, according to NBC. "And therefore, the killing and beheading of innocent people in fact is a matter of shame for them and it's the matter of concern and sorrow for all the human and all the mankind."

Rouhani's comments follow the recent beheadings of captured U.S. journalists James Foley and Steven Sotloff. Last week, a video purporting to show the beheading of British hostage David Haines also emerged. Other hostages also have been purportedly killed by the Islamic militant group.

The interview of Rouhani at his palace in Teheran comes ahead of his visit next week to the United Nations in New York to attend the U.N. General Assembly, where much of the discussion is expected to centre on how to counter ISIS, a common acronym for the Islamic State in Iraq and Syria.

The United States has been trying to build an international coalition to fight the militant group but Iran's supreme leader, Ayatollah Ali Khamenei, this week said he had rejected Washington's offer for talks on the issue.

On Wednesday, U.S. President Barack Obama said so far 40 nations have pledged to help. Obama is expected to meet with his national security team on Wednesday to discuss the UN meeting on ISIS, the White House said.