"We hope we can solve it diplomatically," Bush told NBC television's "Today" show.

"We've had a long policy of sanctions. We can't sanction them anymore. But we can work with others to continue sending a message: We expect them to give up their nuclear ambitions."

Asked whether the country -- which Bush labeled as part of an "axis of evil," along with Iraq and North Korea -- was indeed "evil," the president replied: "I think a country that suppresses their people is not good, and they do.

"They are not listening to the demands of their people. And we are deeply concerned about a country ... that is developing a nuclear weapon, that has supported terrorist groups.

"And we've made our position very clear and are working with others, and that's what we always must do, is always try to work with others to solve a problem before it becomes acute," Bush said.

The US president's administration opposes the activation of Iran's power plant in the Gulf port of Bushehr, which Tehran says is being built exclusively for civilian purposes.

Washington believes Iran, one of the world's largest oil suppliers, has no need for nuclear energy and accuses Tehran of hiding a nuclear weapons development program under the guise of a civilian atomic energy program.