President Obama, hoping for a "new beginning" in relations with Iran, has made a direct videotaped appeal to the country's people and leaders to put years of enmity behind.
The president's appeal, subtitled in Farsi, is timed to coincide with the Iranian New Year.
"We have serious differences that have grown over time," Obama said in the video. "My administration is now committed to diplomacy that addresses the full range of issues before us and to pursuing constructive ties among the United States, Iran and the international community."
"This process will not be advanced by threats. We seek instead engagement that is honest and grounded in mutual respect," he said.
The appeal was not broadcast on Iran's main 2 p.m. state television news, although it was reported by Iranian news agencies including the official agency IRNA.
Aliakbar Javanfekr, an aide to Iranian President Mahmoud Ahmadinejad, issued a cautious response to the White House appeal, saying Tehran welcomed America's interest in settling differences but needed to see more actions to go with the positive words.
"The Iranian nation has shown that it can forget hasty behavior but we are awaiting practical steps by the United States," Javanfekr said. "The Obama administration so far has just talked," he added, calling for Obama to make "fundamental changes in his policy towards Iran."
The United States has no diplomatic relations with Tehran, but Obama has expressed a readiness to have face-to-face diplomatic contacts with Tehran -- a major policy shift toward a country former president George W. Bush branded as part of an "axis of evil."
Obama said the United States wanted Iran to take its "rightful place in the community of nations", but also said Tehran must do its part to achieve reconciliation.
European Union foreign policy chief Javier Solana said he hoped Iran would pay close attention to Obama's appeal.
"I hope that that will open a new chapter in relations with Iran," he told reporters before going into an EU summit.
From NPR staff and wire service reports