Obama ripped Ahmadinejad for saying the United States was responsible for the Sept. 11, 2001, terrorist attacks on New York and the Pentagon.
"Well, it was offensive. It was hateful. And particularly for him to make the statement here in Manhattan, just a little north of Ground Zero, where families lost their loved ones, people of all faiths, all ethnicities who see this as the seminal tragedy of this generation, for him to make a statement like that was inexcusable," Obama said in a BBC interview.
"Again, for Ahmadinejad to come to somebody else's country and then to suggest somehow that the worst tragedy that's been experienced here, an attack that killed 3,000 people, was somehow the responsibility of the government of that country, is something that defies not just common sense but basic sense -- basic senses of decency that aren't unique to any particular country -- they're common to the entire world."
Obama said his administration has reached out to Iran but was forced to impose sanctions because "the government has taken Iran on a path that has led to international condemnation."
"Now, that's a choice that the Iranian regime has made. They can make another choice, and we would welcome them making another choice, which would be to act responsibly. They would then be able to have their rights for a peaceful nuclear program under the Nuclear Non-proliferation Treaty. And that would remove the sanctions and would allow them to fully enter the international community in a way that would tremendously benefit the Iranian people. But we have not seen them make that choice yet."
As he did in his speech to the U.N. General Assembly, Obama called on Iran to prove -- not just say -- its nuclear intentions are peaceful.
On Afghanistan, Obama said the United States will not leave suddenly, "turn out the lights and go home" next July. He said Iran and other nations in the region should play a constructive role in Afghanistan's development although evidence indicates Iran has worked behind the scenes to help insurgents.