The so-called "Burn a Koran Day" ignited a protest for a second day in a row by hundreds of Afghans, who burned American flags and shouted "Death to America."
The crowd in downtown Kabul reached nearly 500 on Monday, with Afghan protesters chanting, "Long live Islam," and, "Long live the Koran," and burning an effigy of Terry Jones, senior pastor from the Dove World Outreach Center in Florida, who is planning the event.
While Jones has an approximately 50-member following in Gainesville, Florida, protesters in Afghanistan were well aware of the pastor's inflammatory comments, such as, "Islam is an evil religion," because they have spread wide on the Internet. Jones also has authored a book, "Islam Is of the Devil."
"America cannot eliminate Muslims from the world," one Afghan man told ABC News.
On Monday, the angry crowd pelted a passing U.S. military convoy with rocks.
Gen. Petraeus said he is outraged by the pastor's decision to burn the Koran, which he said could "endanger troops and it could endanger the overall effort here."
"It puts our soldiers in jeopardy, very likely," he told ABC News Tuesday. "And I think, in fact, images from such activity could very well be used by extremists here and around the world."
White House Press Secretary Robert Gibbs echoed Petraeus' remarks.
"We know that that type of activity's being transmitted back to places like Afghanistan, where Gen. Petraeus obviously is our lead commander," Gibbs said. "As he said, it puts our troops in harm's way. And obviously ... any type of activity ... that puts our troops in harm's way would be a concern to this administration."
Former Vice Chief of Staff of the Army Gen. Jack Keane, an adviser to Petraeus, called Jones' anti-Koran event "outrageous" and "insulting to Muslims."
"It's also insulting to our soldiers in terms of what they stand for and what their commitment is to this country and to the Muslims in this country," Keane told ABC News.
But Jones said today he would go ahead with the Koran burning, despite the concerns of Petraeus and Keane for the safety of U.S. troops.
"Of course we care," Jones told ABC News. "It'd be tragical if because of this one person died. But at the same time, we do not feel responsible for that.
"What we are doing is long overdue," he said. "We are revealing the violence of Islam that is much, much deeper than we'd like to admit."
A Facebook page dedicated to the day, titled "International Burn a Koran Day," has more than 8,000 fans.
"On September 11th, 2010, from 6pm-9pm, we will burn the Koran on the property of Dove World Outreach Center in Gainesville, FL in remembrance of the fallen victims of 9/11 and to stand against the evil of Islam. Islam is of the devil!" the page says.
More than 100 other pages have sprung up for and against the event on Sept. 11, which happens to coincide this year with the Muslim holiday of Eid, celebrating the end of the Islamic holy month of Ramadan. Some Muslims fear that images of celebration could fuel further tensions with Americans that day.
ABC News' Kristina Wong contributed to this report from Washington.