Amid fears that one response might be a US or Israeli strike on Tehran's nuclear programme, a top aide to Iran's supreme leader warned again that Iran could bring oil shipments from the Gulf to a halt if attacked.
"We are against offering the agency an open door once more and that they expect Iran to respond to any claim," said Alaeddin Borujerdi, head of parliament's national security and foreign affairs commission.
On Monday the the International Atomic Energy Agency (IAEA) issued a report accusing Iran of stalling over a probe into its nuclear work and said it was continuing uranium enrichment in defiance of UN demands.
"We do not think there should be an open forum so America can bring up a new claim every day and pass it on to the agency, expecting Iran to address any claim," Borujerdi said.
Iran's envoy to the IAEA also warned that Tehran would only cooperate within the framework of the nuclear Non-Proliferation Treaty and its safeguard agreements.
"We continue cooperating with the IAEA but they should not expect us to apply the additional protocol," said Ali Asghar Soltanieh.
Iran stopped applying the additional protocol, which gives inspectors broader access to its nuclear sites, after the nuclear case was referred to the UN Security Council in 2006.
The IAEA complained it was making little headway in probing allegations that Tehran has been involved in studies to make a nuclear warhead, as Iran refused to provide access to documentation, individuals or sites that could reveal the true nature of its activities.
Tehran said the alleged weapon-related studies were based on fabricated documents and that it had provided the IAEA a 117-page response in May addressing some of the agency's questions.
The United States, which is spearheading moves against Iran's nuclear drive, and France warned that Tehran could face possible new sanctions in the wake of the IAEA report. China said sanctions would not resolve the stalemate.
High-ranking diplomats from the United States, China, Russia, Britain, France and Germany were to meet in Washington on Friday to discuss Iran's nuclear drive, US officials said.
Uranium enrichment lies at the core of fears about Iran's nuclear programme, as the process can make nuclear fuel as well as the fissile core of an atom bomb.
Iran denies Western claims it is seeking to build atomic weapons, insisting that it wants nuclear power to provide energy for a growing population.
Amid high diplomatic tensions, a former head of Iran's Revolutionary Guards repeated an oft-stated warning that those forces could halt vital shipping in the Gulf.
Their missiles can cover the entire width of the Gulf and "no ship can cross it without being within range", said General Rahim Yahya Safavi, now an aide to supreme leader Ayatollah Ali Khamenei.
"Our armed forces with their defence equipment including missile, air, naval and torpedo capabilities are able to control the Strait of Hormuz."
Iranian Defence Minister Mustafa Mohammad Najjar told reporters in Doha that he did not expect the United States to attack, but if they did the response would be "decisive."
"We believe that America will not dare attack Iran, particularly because of the international and regional conditions it is facing and its domestic problems."
Najjar added that Iran "has taken all the necessary measures to ensure the security of" the Strait of Hormuz.
An estimated 40 percent of the world's oil passes through the Strait, a narrow channel between Iran and Oman.
The Guards form the country's ideological army, with their own ground, navy and air forces operating in parallel with the regular armed forces.
Referring to a potential Israeli attack, Safavi said: "The Zionist regime does not have the necessary political, economic and social capabilities to wage a great war."
He also warned US military forces in the region of "serious danger" in case of war, but said he believed Washington "will definitely not get involved in a fourth front after the Afghanistan, Iraq and Georgia confrontations."
