The US has vowed to push for further UN sanctions against Iran, following the latest report on its nuclear programme.
President Ahmadinejad says Iran's nuclear programme is peaceful
The UN's nuclear watchdog said Tehran had made moves towards transparency, but was continuing to enrich uranium in defiance of the Security Council.
The White House said "selective co-operation" was "not good enough".
The US and its allies fear Iran is building a nuclear weapons capability. Tehran denies this and insists the report gave it a clean bill of health.
The UN's International Atomic Energy Agency (IAEA) reached a deal in August with Iran, according to which Tehran would answer outstanding questions as part of a four-year probe into its nuclear drive.
The latest IAEA report praised Iran for making progress in responding to questions about past activities.
"Iran has provided sufficient access to individuals and has responded in a timely manner to questions and provided clarifications and amplifications on issues raised in the context of the work plan," the report said.
However, it said Iran's co-operation had been "reactive" rather than "pro-active" and that the IAEA was continuing to check whether Iran's declarations were complete.
The report also found that the agency's knowledge about Tehran's current nuclear programme was diminishing.
It says the government had been operating 3,000 centrifuges, the machines used to enrich uranium, at its plant at Natanz.
"Contrary to the decisions of the Security Council, Iran has not suspended its enrichment related activities," the document says.
White House spokeswoman Dana Perino said: "This report indicates that Iran continues to defy the international community and two unanimous UN Security Council resolutions."
She added that the documents made it "clear that Iran seems uninterested in working with the rest of the world".
Ms Perino said the US would work towards a new set of Security Council sanctions when representatives of the five permanent members, along with Germany, meet on Monday in Brussels.
Western powers are concerned because, while enriched uranium is used as fuel for nuclear reactors, highly enriched uranium can also be used to make nuclear bombs.
Two UN Security Council resolutions approved in March impose limited sanctions on Iran.
These include a ban on arms sales and restrictions on financial assistance.
In September, council members agreed to delay a vote on further measures until the publication of the present report.
Top Iranian nuclear negotiator Saeed Jalili said the report proved that accusations against his country were baseless and new sanctions would be wrong.
"When the IAEA clearly announces that we were cooperating and the main reason to send Iran's case to the UN Security Council no longer exists, then why should there be another resolution against us?" he said in Tehran.