The announcement, which followed a meeting involving President Saddam Hussein and senior officials, accused the United States of trying to push a "new, bad" resolution.
US President George W Bush is calling for the Security Council to lay out specific consequences for Iraq if it fails to comply fully with existing resolutions on weapons inspections.
The American general who would lead a US military campaign against Iraq said on Saturday his forces were ready for war.
"We are prepared to do whatever we are asked to do," General Tommy Franks said on a visit to troops stationed in Kuwait.
General Franks insisted Mr Bush had not taken a final decision on military action but senior US officials admitted that Mr Bush had now been given a detailed set of military options.
"I am not saying there is no plan on his desk," White House spokesman Ari Fleischer said.
Council split
Iraq agreed on Monday to allow the unconditional return of international weapons inspectors who left the country four years ago.
The BBC's Caroline Hawley in Baghdad says Iraq made it clear it expected the UN in return to guarantee it would not face attack if they did come back, and that it also wanted light at the end of the tunnel over sanctions.
"Iraq announced that it will not co-operate with a new resolution which is different to what was agreed with the (UN) Secretary General (Kofi Annan)," Saturday's statement said.
"American officials are trying to issue or pass a new, bad resolution by the Security Council," it said.
The new Iraqi stand was decided at a meeting between Saddam Hussein and senior officials, including Foreign Minister Naji Sabri who has just returned from the UN.
The five permanent members of the Security Council have been split over the US demand for a resolution, with the UK backing Mr Bush, Russia and China opposing a new resolution and France expressing strong reservations.
The US has dismissed the Iraqi offer to resume inspections as a ploy and Mr Bush has asked Congress to authorise measures against Iraq even if the UN refuses to do so.
War plans
US military plans for action against Iraq have already been worked out in some detail, US officials have said.
Highly classified plans were presented to Mr Bush in early September, just days before his speech to the UN General Assembly demanding its support, the New York Times said, quoting unnamed officials.
They told the paper any attack would start with heavy air bombardments by B2 bombers aimed at destroying air defences, command and control headquarters and communications structures, leaving President Saddam isolated in Baghdad.
Meanwhile, tens of thousands of marines and soldiers would launch an assault from Kuwait and possibly other countries.
The planning document also gives the number of ground troops, combat aircraft and aircraft carrier battle groups required, officials told the New York Times.