He said: "He's going to be making some calls, but my general belief is that when it comes to national security, what we have to focus on is getting things right in the future, as opposed to looking at what we got wrong in the past."
The incoming president told ABC's This Week presenter George Stephanopoulos he would break away from President George W Bush's policy on Iran and seek a much broader approach with the Islamic state.
"We are going to have to take a new approach. And I've outlined my belief that engagement is the place to start," Mr Obama said.
Mr Obama, who won the US presidential election in November, takes office on 20 January.
Iran's nuclear programme is causing concern in the West
In the interview, he promised "a new emphasis on respect and a new emphasis on being willing to talk, but also a clarity about what our bottom lines are."
He added he believed his administration would "move swiftly" in its new approach with Tehran.
Mr Obama had earlier said there should be no pre-conditions in discussions with the Iranian leadership.
The Bush administration had accused Iran of developing nuclear technology in order to produce nuclear weapons, but Iran has insisted the processes will only be used to generate electricity.
'Failure of supervision'
"Iran is going to be one of our biggest challenges and as I said during the campaign we have a situation in which not only is Iran exporting terrorism through Hamas, through Hezbollah but they are pursuing a nuclear weapon that could potentially trigger a nuclear arms race," Mr Obama said.
Mr Obama also said a new team would begin work on a wider Middle East peace process when he began his presidency.
"What I am doing right now is putting together the team so that on 20 January, starting on day one, we have the best possible people who are going to be immediately engaged in the Middle East peace process as a whole," Mr Obama said.
On the economy, Mr Obama said he was dissatisfied with the way the first $350bn (£229bn) in the Troubled Asset Relief Program (Tarp) had been spent after it was approved by Congress last year.
"There hasn't been enough oversight," Mr Obama said. "We found out this week in a report that we are not tracking where this money is going."
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