Russian and Chinese objections to a draft statement United Nations Security Council on Iraq's revived nuclear programme has led to the postponement of a closed-door meeting scheduled for today.
No date has been set for a new meeting but envoys said informal contacts among members would continue throughout the day.
The draft statement tells Iran to suspend all uranium enrichment activities and comply with demands from the International Atomic Energy Agency (IAEA) in Vienna.
The meeting was called after the IAEA referred Iran's resumption of its nuclear enrichment programme to the Security Council after it refused to allow unscheduled IAEA inspections of its nuclear facilities.
Many in the international community believe the Iranians are attempting to develop a nuclear missile capability.
Iran has repeatedly stressed that it will continue to honour its commitments under the Nuclear Non-Proliferation Treaty but that it has the right to pursue a peaceful nuclear program.
Iran later said it would not be bullied by the United States and was not concerned about the United Nations proceedings.
"We emphasise that nuclear technology and the nuclear fuel cycle is our absolute right. The nation, I and other officials will not yield to America's bullying language by any means." Supreme Leader Ayatollah Ali Khamenei said in a televised speech.
"They are threatening us with the Security Council as if the Security Council is the end of the world," Ayatollah Khamenei said.
"We had experience of the Security Council [threats] at the time of the war with Iraq. Whatever is against the interest of the country we will not accept."
The United States, Britain and France want the Security Council to spearhead the investigation of Iran's nuclear programme.