WASHINGTON?US President Barack Obama on Friday forcefully defended his handling of a Florida pastor's threats to burn the Koran, saying he aimed to head off any copycat demonstrations.

"Although this may be one individual in Florida, part of my concern is to make sure that we don't start having a whole bunch of folks all across the country thinking this is the way to get attention," said Obama.

The president, speaking at a formal White House press conference, pointedly did not mention pastor Terry Jones by name as he rejected any suggestion that top US officials had "elevated" the controversy from local flap to global uproar.

"I hardly think we're the ones who elevated this story. But it is, in the age of the Internet, something that can cause us profound damage around the world and so we've got to take it seriously," he said.

"This is a way of endangering our troops, our sons and daughters, fathers and mothers, husbands and wives who are sacrificing for us to keep us safe. You don't play games with that," said Obama.

His comments came after the US commander in Afghanistan, General David Petraeus, denounced Jones's plans and US Defense Secretary Robert Gates telephoned the pastor to plead that he abandon his incendiary gesture.

"We've got an obligation to send a very clear message that this kind of behavior or threats of action put our young men and women in harm's way. And it's also the best imaginable recruiting tool for Al-Qaeda," said Obama.

The US president reiterated his view that "the idea that we would burn the sacred texts of someone else's religion is contrary to what this country stands for. It's contrary to what this nation was founded on."

"And, you know, my hope is that this individual prays on it and refrains from doing it," he said.