"We welcome change but on condition that change is fundamental and on the right track," he said.
The new administration has said Obama would break from his predecessor by pursuing direct talks with Tehran but has also warned Iran to expect more pressure if it did not meet the UN Security Council demand to halt its disputed nuclear work.
Washington and its Western allies accuse Iran of seeking to build nuclear weapons. Tehran denies the charge and refuses to give up work it insists is its sovereign right.
Ahmadinejad listed during his speech a range of "crimes" against Iran, such as trying to block what Tehran says is a peaceful nuclear power generation program, hindering Iran's development since the 1979 revolution and other actions by several administrations for more than 60 years.
Iran has in the past told Washington that it should withdraw its troops from the region.
Ahmadinejad, in his speech, said: "Who has asked them (the United States) to come and interfere in the affairs of nations?"
As well as saying Tehran wants nuclear arms, Washington accuses Iran of sponsoring "terrorists" and undermining efforts to make peace in the Middle East between Israel and Arabs.
Echoing Obama's remarks, U.S. Secretary of State Hillary Clinton signaled the administration's readiness to talk to Iran, saying Tehran had a "clear opportunity" to show the world it is willing to engage.