BRUSSELS, Belgium – President Bush said yesterday that it is “simply ridiculous” to assume that America has plans to attack Iran over its alleged nuclear weapons program.

“This notion that the United States is getting ready to attack Iran is simply ridiculous. Having said that, all options are on the table,” Mr. Bush said after discussing the issue with European allies.

Mr. Bush used his bluntest language yet to reassure Iran’s leaders. Last week, in a series of pre-trip interviews with European journalists, he also tried to dispel talk of a military attack, an issue that has been raised repeatedly since America went to war with Iraq primarily over its alleged weapons of mass destruction. No such weapons have been found in Iraq.

On Iran, Mr. Bush has walked a careful line in expressing support for a European-led approach offering Iran technological, financial, and political support in return for scrapping its uranium enrichment program.

“It’s in our interests for them not to have a nuclear weapon,” Mr. Bush said in a news conference with European Union leaders.

America has refused to get involved in the bargaining with Tehran or to make commitments about incentives, insisting that Tehran abandon its program.

Also on Tuesday, Bush hailed NATO’s modest pledge to help train security forces in Iraq, saying “every contribution helps.”

“The NATO training mission is an important mission, because after all, the success of Iraq depends upon the capacity and the willingness of the Iraqis to defend their own selves against terrorists,” he said during an earlier news conference at NATO headquarters.

Mr. Bush also reiterated American opposition to Europe’s plans to lift its 15-year arms embargo against China.

“There is deep concern in our country that a transfer of weapons will be a transfer of technology, that it will change the balance of relations between China and Taiwan,” Mr. Bush said.

He said he understands that the Europeans are working on a way to address American worries about allowing China to modernize its military with arms and communications, intelligence, and surveillance equipment that would give Beijing an edge over Taiwan.

“They know the Congress is concerned,” Mr. Bush said. “And so they’ll try to develop a plan that will ease concerns. Now, whether they can or not, we’ll see.”

But French President Chirac, while stressing that security guarantees could be worked out, indicated that Europe remains steadfast in its desire to end the ban. “We intend to lift the last obstacles in our relations (with China), and this within a spirit of responsibility,” he said.

In Beijing yesterday, Chinese Foreign Ministry spokesman Kong Quan said that abolishing the “erroneous and outdated measure” would help move China-E.U. relations forward.

As Mr. Bush shuttled in between NATO headquarters and meeting with European Union leaders, opposition to the American president was evident in the streets of Brussels as protesters lobbed a fire bomb at riot police. Police responded with water cannons to disperse the crowd that they estimated was 1,000 strong.

Police said they did not know if anyone was injured. Associated Press Television News reporters saw several people arrested.

On Iraq, Luxembourg Prime Minister Jean-Claude Juncker, whose country holds the rotating European Union presidency, said America and the E.U. will host a conference to rally international support for Iraq if the new government there requests it.

NATO, meanwhile, succeeded after struggling for months to get a commitment from all allies to join the mission in Iraq, including those that vigorously opposed the American-led war there.

“All 26 allies are working together to respond to the Iraqi government’s request for support by training Iraqi security forces, providing equipment, and helping to fund NATO’s efforts,” Jaap de Hoop Scheffer told the NATO summit.

The development of a reliable Iraqi security force, so that Iraqis can handle their own security, is considered vital to lowering the American troop presence there.