The New York imam leading efforts to build an Islamic centre near the World Trade Center site says plans by a small US church to burn Korans would have sparked "a disaster".
Feisal Abdul Rauf told ABC News that the event - now called off - would have "strengthened radicals".
Rallies for and against the proposed centre marred the 9/11 commemorations.
Meanwhile, two people died in eastern Afghanistan as protests sparked by the threatened book burning continued.
Security forces opened fire when some demonstrators tried to storm the district governor's office in Baraki Barak, in Logar province, on Sunday.
Protests have erupted across the Muslim world since Florida Pastor Terry Jones announced plans to burn Korans outside his church to mark the 9/11 attacks.
Mr Jones said he cancelled the event because those behind the Islamic centre near Ground Zero had agreed to relocate it - a claim denied by Mr Rauf.
"How can you equate the burning of any person's scripture with an attempt to build inter-faith dialogue?" Mr Rauf told ABC.
"This is a house with multi-faith partners, intended to work together towards building peace".
He said burning the Koran would have sparked "a disaster" in the Muslim world.
"It would have strengthened the radicals. It would have enhanced the possibility of terrorist acts against America and American interests," he said.
The group led by Mr Rauf hopes to turn an abandoned building into a community centre and prayer space.