Mr. Bush said his goal is to keep the Iranians from having the capability or the knowledge to have a nuclear weapon.
"I know we're here in Washington (where) prevention means force," Mr. Bush said. "It doesn't mean force necessarily. In this case it means diplomacy."
Mr. Bush and other administration officials have said repeatedly that the military option is on the table, CBS News White House correspondent Bill Plante reports, and White House officials acknowledge "normal" military planning is under way. Several reports published over the weekend said the administration was studying options for military strikes, and an account in The New Yorker magazine by Seymour Hersch raised the possibility of using nuclear bombs against Iran's underground nuclear sites.
Mr. Bush did not directly respond to that report but said, "What you're reading is just wild speculation."
But Mr. Bush said he was correct to include Iran in the "axis of evil" with Iraq and North Korea and he's glad to see other countries taking the threat from Iran seriously, too.
"I got out a little early on the issue by saying axis of evil," Mr. Bush said. "But I meant it. I saw it as a problem. And now many others have come to the conclusion that the Iranians should not have a nuclear weapon."
The White House sought Monday to minimize new speculation about a possible military strike against Iran while acknowledging that the Pentagon is developing contingency plans to deal with Tehran's nuclear ambitions. The Pentagon has refused to further describe its planning.
White House press secretary Scott McClellan refused to confirm or deny a report in The New Yorker magazine that raised the possibility of using nuclear bombs against Iran's underground nuclear sites.
"Those who are seeking to draw broad conclusions based on normal military contingency planning are misinformed or not knowledgeable about the administration's thinking," he said.
The New Yorker article quotes one former senior intelligence official as saying that Mr. Bush views Iran's President Mahmoud Ahmadinejad as a "potential Adolph Hitler," and Hersch says some inside the Pentagon have proposed using tactical nuclear weapons to penetrate the increased defenses.
Hersch tells CBS News' The Early Show there is "a lot of debate" over whether to launch a nuclear attack.
"Nobody in the Pentagon seriously thinks that it could be an option. It's an impossible option. They wanted to get rid of it," Hersch says. "And as I write, they are going to come back to the president with a formal recommendation that they take this option out of the plan. And if it doesn't happen some people are willing to claim they will actually resign over the issue."
Hersh also tells Early Show co-anchor Hannah Storm that while the administration is publicly advocating diplomacy, there are clandestine American forces in Iran right now.
"They're on the ground, they're collecting intelligence. They're talking to the ethnic minorities inside Iran that oppose the government and they're also getting ready to pick target," Hersh says. "In order for the bombs to be accurate, men on the ground have to be there to paint the target. It's all part of the obvious planning for an offensive if we decide to have one."