(CNN) -- Iran said Tuesday the Bush administration must "pay the price" for what it called "lies" concerning Tehran's nuclear program.
A file satellite image shows Iranian nuclear facilities.
A declassified summary of a National Intelligence Estimate released by the U.S. government on Monday said Iran had stopped working toward a nuclear weapon in 2003 and is unlikely to be able to produce enough enriched uranium for a bomb until at least 2010.
The estimate is less severe than a 2005 report that judged the Iranian leadership was "determined to develop nuclear weapons despite its international obligations and international pressure."
On its Web site, Iran's official Islamic Republic News Agency called the updated estimate "a necessary and positive step in Tehran-Washington relations, but undoubtedly is not sufficient."
"The U.S. administration should know that only admitting a mistake is not enough," the IRNA report said.
Iranian government spokesman Gholam-Hossein Elham, quoted on the IRNA site, was more harsh but offered no specifics.
"U.S. officials have so far inflicted ... damage on the Iranian nation by spreading lies against the country and by disturbing public opinion, therefore, they have to pay the price for their action," Elham is quoted as saying.
President Bush was expected to face questions about the Iran report at a Tuesday morning news conference.
U.S. national security adviser Stephen Hadley expressed hope after Monday's announcement of the new estimate, but he said Iran remains a serious threat.
"We have good reason to continue to be concerned about Iran developing a nuclear weapon even after this most recent National Intelligence Estimate," he told reporters at the White House. "In the words of the NIE, quote, Iranian entities are continuing to develop a range of technical capabilities that could be applied to producing nuclear weapons, if a decision is made to do so."
He said that technology developed for Iran's civilian nuclear power program could help enrich uranium for use in weapons and that Iran is continuing to develop ballistic missiles.
Hadley said U.S. policy toward Iran has not changed because of the new report.
"If we want to avoid a situation where we either have to accept Iran ... with a path to a nuclear weapon, or the possibility of having to use force to stop it, with all the connotations of World War III -- then we need to step up the diplomacy, step up the pressure, to get Iran to stop their so-called civilian uranium enrichment program," he said. "That's our policy going forward -- no change."
Britain on Tuesday also called for continued pressure on Iran.
"The report confirms that we were right to be worried about Iran seeking to develop nuclear weapons, and it also shows that the sanctions program and international pressure were having some effect," a spokesman for Prime Minister Gordon Brown said.
"But it also tells us that the intent was there, and the risk of Iran acquiring nuclear weapons remains a very serious problem.
"While this report seems to show the Iranians have moved away from producing weapons-grade uranium, the real worry is that they still may be continuing to move forward with enrichment and processing."
Enriched uranium at low concentrations can be used to fuel nuclear power plants, but much higher concentrations are needed to yield a nuclear explosion.
"We judge with moderate confidence that the earliest possible date Iran would be technically capable of producing enough highly enriched uranium for a weapon is late 2009, but that this is very unlikely," the new estimate says. A more likely time frame for that production is between 2010 and 2015, it concludes. 
Watch what new report says about Iran's nuclear ambitions »
Iran has insisted its nuclear program is strictly aimed at producing electricity, and the country has refused the U.N. Security Council's demand to halt its enrichment program.
Monday's report represents the consensus of U.S. intelligence agencies. It suggests that a combination of "threats of intensified international scrutiny and pressures, along with opportunities for Iran to achieve its security, prestige and goals for regional influence in other ways," could persuade the Iranian leadership to continue its suspension of nuclear weapons research.
Available intelligence suggests the Iranian leadership is guided "by a cost-benefit approach," not a headlong rush to develop a bomb, the report concludes.
The International Atomic Energy Agency, the U.N. nuclear watchdog, has reported that Iran is cooperating with inspectors by providing access to declared nuclear material, documents and facilities. However, the agency also said Iran is withholding information in other areas, and as a result, the IAEA's knowledge about the status of the program is "diminishing."
Iran says its uranium enrichment work is allowed under the 1968 Non-Proliferation Treaty. The U.N. Security Council has passed two rounds of sanctions against Tehran, but Washington missed its goal of reaching consensus on tighter restrictions by the end of November, the State Department said last week.
The report comes amid widespread accusations that the Bush administration is attempting to maneuver the United States into a conflict with Iran, which it accuses of meddling in the war in Iraq. In October, the United States designated elements of Iran's Revolutionary Guard Corps as supporters of terrorism.
