ElBaradei called for greater US participation in diplomatic efforts to engage Iran and North Korea in talks about their nuclear programs.
"North Korea and Iran are still the two 800-pound gorillas in the room and not much is happening," ElBaradei told The Washington Post at his IAEA office in Vienna. The daily said the interview was with four US newspapers.
The IAEA chief praised Britain, France and Germany for talking Iran into suspending its nuclear enrichment program for weapons-grade uranium.
"If I look at the big picture," he said, "there is no enrichment in Iran, and this is quite satisfactory, and I hope it keeps this way until we reach an agreement" for a permanent stop.
Iran and the EU embarked in December on negotiations towards a long-term agreement to give Tehran trade, technology and security aid and guarantees in return for it taking steps to reassure the international community that its nuclear program is strictly peaceful.
ElBaradei criticised Washington's refusal to talk with Iran, dismissing the argument that this would legitimise Tehran's Islamic government, which the United States accuses of supporting terrorism.
"I don't see talking to a regime as legitimisation," ElBaradei said. "They talk to North Korea, and I don't think that legitimises the North Korean regime."
He insisted that the only way to end the crisis with Iran was for the United States to join in the talks with its three European allies.
"I don't think the Iranian issue will be resolved without the United States putting fully its weight behind the Europeans," he said.
On North Korea's announcement last week that it had built nuclear weapons and was pulling out of six-nation talks about its atomic programme, ElBaradei said his agency could not verify Pyongyang's claim since its inspectors in the Stalinist nation were expelled two years ago.
However, he considered the North Koreans' announcement a sign that they were feeling ignored: "This is their trump card, and they will try to squeeze every drop of blood out of it."
ElBaradei urged the United States, China, Japan, South Korea and Russia to coax North Korea into accepting IAEA inspections once again, "the sooner, the better." On Washington's intention to have him step down when his second term as IAEA chief ends in mid-2005, ElBaradei said his relations with the United States have been good: "I would hope we would continue to co-operate no matter what."