Millions of people protested in hundreds of cities around the world against a U.S.-backed military action that would force Baghdad to comply with a United Nations call to abandon alleged weapons of mass destruction programs.
Mr. Bush said that war remains a last resort, but told reporters that "the risk of doing nothing is even a worse option as far as I'm concerned."
"Some in the world don't view Saddam Hussein as a risk to peace," the president said. "I respectfully disagree."
The president said that the size of the protests -- with as many as 7.5 million people participating across the globe -- would not weigh on his final decision whether to go to war.
"Size of protest, it's like deciding, 'Well, I'm going to decide policy based up on a focus group,'" Mr. Bush said. "The role of a leader is to decide policy based upon the security -- in this case -- security of the people."
At one protest in New York on Sunday, Archbishop Desmond Tutu railed against a potential pre-emptive strike on Iraq, saying world powers should let diplomacy run its course.
"Any war, before you have exhausted all possible peaceful means, is immoral," Tutu said. "And those who want to wage war against Iraq must know it would be an immoral war."
Also Sunday, former senator and onetime presidential candidate George McGovern, a World War II veteran and longtime peace activist, told demonstrators in Montana that he's "tired of old men dreaming up wars for young men to die in."
Mr. Bush's recommitment to the U.S. plan to use force against Iraq if necessary comes as American and British diplomats prepared to argue for a second U.N. Security Council resolution explicitly backing a military strike in Iraq.
"We are working with our friends and allies to see if we can get a second resolution," Mr. Bush told reporters Tuesday, although he underscored his position that the U.S. already has the authority to attack Iraq.
U.S. and British diplomats reportedly met Monday to work out the details of the proposed resolution. However, French President Jacques Chirac said his country would oppose such a move.
"We consider that war is always, always the worst solution," Chirac told reporters Monday.
A draft of the proposed resolution is not expected to emerge until Wednesday at the earliest, Reuters reported. Security Council members are scheduled to meet Tuesday and Wednesday to hear the views of some 40 non-members on the Iraq debate. The meeting was called by South Africa, which chairs the Non-Aligned Movement of some 115 developing countries, many of whom oppose an Iraq war.