"There's been a lot of mistrust built up over the years, so it's not going to happen overnight," said the president.
He stressed, however, that the administration has deep concerns about Iranian policy, noting that the country's "actions over many years now have been unhelpful when it comes to promoting peace and prosperity."
President Obama cited Iran's support for Hezbollah and Hamas, its "bellicose" language toward Israel, and its pursuit of a nuclear weapon.
Obama's Strategy For Iran
He said Iran must understand that the U.S. finds Iranian actions such as funding of terrorist groups unacceptable.
But he added that "there's a possibility, at least, of a relationship of mutual respect and progress."