The United States said a resolution on Wednesday circulating among the International Atomic Energy Agency's (IAEA) board members would tell Iran it would be punished if it defied the watchdog.
But it stopped short of reporting Tehran to the UN Security Council for possible sanctions.
"The three European countries tried their best. We expected more from our European colleagues," Ambassador Pirooz Hosseini told reporters, describing the US approach to discussions in the governing board as an "act of bullying".
"We think that a lot of bullying is involved by the Americans to subdue a healthy process here," Hosseini said.
The IAEA is holding a meeting on Iran in Vienna, at which the United States had insisted that Iran be declared in breach of its international agreements, including uranium enrichment and plutonium processing.
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US officials allege that those activities point to a nuclear weapons agenda, allegations Iran categorically denies.
In the draft, the United States compromised with Britain, France and Germany to tone down criticism of Iran's continued nuclear secrecy and give some praise of Tehran's willingness to open its programmes to outside inspection.
The preliminary draft is still being revised by co-authors Australia and Canada.
Last month, the EU’s "big three" told Iran they would try to block any resolution on Tehran's nuclear programme in exchange for Iran's promise to suspend everything related to its uranium enrichment programme.
But they later agreed to back a resolution that did not report Iran to the council.
Meanwhile, Iranian Foreign Minister Kamal Kharrazi said Tehran will resume uranium enrichment once its problems with the IAEA are resolved and warned European partners it could end nuclear cooperation if they fail to support Tehran.
"America operates a rigorous double standard with respect to nuclear issues, rather like confirmed alcoholics complaining about teenage drinking"
arms control expert
"It's our legitimate right to enrich uranium," Kharrazi told reporters on Wednesday after a cabinet meeting.
But IAEA director general
Muhammad al-Baradai urged Tehran not to resume its uranium enrichment activities as a confidence-building measure.
Kharrazi also warned that Iran could end nuclear cooperation and called on its European partners to resist US pressure at the Vienna meeting.
"We recommend the three European countries to remain committed to their obligations (toward Tehran) and resist US pressures if they want the project of cooperation between Iran and them to lead to results," he said.
Halt in cooperation
The Iranian foreign minister also warned that Iran would stop cooperating with the three nations if they fail to support Iran.
"Cooperation is a two way street. If they don't fulfil their obligations, there is no reason for us to cooperate," he said.
Iran says it wants the West to provide it with nuclear technology for peaceful purposes, an obligation nuclear-capable powers agreed to when they signed up to the Nuclear Non-Proliferation Treaty (NPT).
But the West claims the oil-rich country is not in need of nuclear energy and suspects it of developing weapons.
An IAEA report last month accused Iran of trying to hide evidence of nuclear experiments and mentioned finding traces of polonium, a radioactive element that can be used in nuclear weapons.
Hypocrisy and Israel
It also expressed concerns about the discovery of a previously undisclosed advanced P-2 uranium centrifuge system, a find IAEA director-general Muhammad al-Baradai described as "a setback to Iran's stated policy of transparency".
International arms control expert Dan Plesch said the US pressure on Iran exposed the hypocrisy of nuclear powers.
Israel's reactor is at the heart of
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"America operates a rigorous double standard with respect to nuclear issues, rather like confirmed alcoholics complaining about teenage drinking. Between them the US and Russia have more than 10,000 nuclear weapons yet there is no discussion on their removal," said Plesch, senior research fellow at London University's Birkbeck College.
US strong-arming also exposed the limits of a process that tackled non-proliferation without the inseparable issue of disarmament.
"There are two deals in the NPT. States that didn't go for the bomb got a clause saying they would get help with civil programmes," said Plesch.
"The second was that nuclear states would get rid of their nuclear weapons. Of course that hasn't happened, so they are in breach of their obligations."
The US was also keen to curtail Iran's power vis-a-vis its main regional rival, Israel, the Middle East's biggest nuclear power. But, he added, the international community should not expect Tehran not to pursue nuclear arms while Israel continued to possess them.
"In the same way that Iran, Iraq, Libya issues are being resolved, there is no justification for not addressing the Israel issue. One has to address the issue in a regional arms context," said Plesch.
"It's vastly more practical than people realise if you look at the treaties drawn up at the end of the Cold war. If you could get a deal between Soviets and Reagan, there can be no reason that you cannot get a deal in the Middle East."