U.S. President George W. Bush says U.S. forces in Iraq will stop Iranians if they get in the way of America's plans to stabilize the country.

But he denied that the U.S. plans to carry the fight into Iran.

The United States has blamed Iran for backing Shia militants, who are fighting with Sunnis in the sectarian violence racking Iraq.

"Our policy is going to be to protect our troops in Iraq. It makes sense that if somebody is trying to harm our troops, or stop us from achieving our goal, or killing innocent citizens in Iraq, that we will stop them," Bush said Friday in response to a question about Iran.

"Now some are trying to say that because we're enforcing — helping ourselves in Iraq by stopping outside influence from killing our soldiers or hurting Iraqi people — that we want to expand this beyond the borders. That's a presumption that simply is not accurate."

U.S. officials have said that Iran's support for the insurgents in Iraq includes supplying bombs and other hardware.

"As a result, American forces, when they receive actionable information, may take the steps necessary to protect themselves as well as the population," said Gordon Johndroe, spokesman for the National Security Council, which advises the president.

Bush said in his Jan. 10 televised speech that the U.S. would take a harder line against insurgents. To win in Iraq, the U.S. must confront "extremist challenges," he said.

Iran and Syria "are allowing terrorists and insurgents to use their territory to move in and out of Iraq. Iran is providing material support for attacks on American troops," he said.

"We will disrupt the attacks on our forces. We'll interrupt the flow of support from Iran and Syria. And we will seek out and destroy the networks providing advanced weaponry and training to our enemies in Iraq."

U.S.-led forces have detained five Iranians seized Jan. 11 from an Iranian government liaison office in Irbil, Iraq.

The U.S. administration said the five were linked to violence in Iraq.

But Iraqi Foreign Minister Hoshyar Zebari said the Iranians were working with Iraq government approval.

With files from the Associated Press