"We will take part in the Sharm al-Shaikh conference with force," foreign ministry spokesman Hamid Reza Asefi said.
He said Iran would "protest against the methods of the United States, insist on the necessity of withdrawing US troops from Iraq and the organisation of elections on schedule".
The two-day Iraq conference opens in the Egyptian resort on Monday.
The conference will be held amid tight security after the 7 October bombings in other Red Sea resorts that killed 34 people.
The gathering of 20 foreign ministers and four international organisations has been in the pipeline since Iraq's interim Prime Minister Iyad Allawi called for an international forum during a Cairo visit in July.
US Secretary of State Colin Powell, whose resignation was announced last week, threw his weight behind the conference to rally international support for efforts to restore order in violence-wracked Iraq.
The forum will bring together the US and United Nations, whose Secretary-General Kofi Annan angered Washington in September when he declared the Iraq war "illegal".
France's Jacques Chirac doubts
world is safer after Iraq invasion
He went on to warn before the Falluja assault that it could undermine the Iraqi elections rather than clear an obstacle to the polls.
Before the meetings, French President Jacques Chirac and UK Prime Minister Tony Blair tried to put their differences over last year's invasion behind them with a joint call on Thursday for a "stable and democratic Iraq".
But the French leader still aired his doubts over whether the world had become a safer place since the invasion.
Iraq's neighbours Syria and Turkey, which are to meet first on Monday before plenary sessions, have sought to coordinate their position, especially their concerns over Kurdish autonomy.
Syrian Foreign Minister Faruq al-Shara, on a visit to Ankara, said the neighbouring states should assert their opposition to any moves that might harm Iraq's territorial integrity.
Syria and Turkey will focus on
Kurdish aspirations for self-rule
Both Ankara and Damascus fear that Iraqi Kurdish aspirations for greater self-rule could destabilise their own Kurdish regions.
The conference will also bring together Iraq's interim government with officials from the Group of Eight industrialised nations, the Arab League and Organisation of the Islamic Conference (OIC).
Alongside Powell will be French Foreign Minister Michel Barnier, who tried but failed to have Iraqi opposition figures allowed to attend, as well as his opposite numbers from Britain and Germany, Jack Straw and Joschka Fischer.
A 14-point draft Sharm al-Shaikh declaration is based on an Egyptian text that was amended during several preparatory meetings held in Cairo, amid wrangling between France and the US.
It stresses "the leading role of the United Nations in supporting, as circumstances permit, the political process in Iraq", especially in providing support for the holding of elections by the end of January.
The conference will be held amid
tight security at Sharm al-Shaikh
The draft also calls on Iraq's neighbours "to prevent the transit of terrorists to and from Iraq, arms for terrorists", and to step up cooperation on border control.
While not setting a time limit for the deployment of the US-led forces, it reiterates that their mandate is "not open-ended".
Powell, meanwhile, said Iran's disputed nuclear programme would also figure on the agenda, after an accord negotiated last week by the EU.
Asefi said Tehran would directly spell out its position to the US during the conference, but no bilateral meeting was on the agenda.