Iran "will accept for its best interests and out of concern for its honour, but with conditions and reservations that have to be taken into account," said Yunessi, quoted by state news agency Irna.
In a resolution on September 12, the International Atomic Energy Agency (IAEA) gave Iran until October 31 to guarantee it was not and would not develop atomic weapons under the cover of its civil nuclear program.
The resolution also called on it to sign an additional protocol of the UN nuclear Non-Proliferation Treaty and implement it immediately and unconditionally.
Yunessi said Iran, as a member of the IAEA, ought to have the same technological assistance with its nuclear programme as is given to other states, but that this aid had been denied because of "American pressure."
Earlier Saturday, Iran's representative to the IAEA Ali Akber Salehi said that Teheran and the Vienna-based UN watchdog had set the "dimensions and the framework" for inspections of the Islamic republic's nuclear facilities.
Salehi did not specify what the "dimensions" were, but said discussions between Iranian officials and IAEA delegation head Pierre Goldschmidt "ended in total optimism and the satisfaction of both parties."
He did not say to what extent the Iranians would cooperate with inspectors, whose new mission in Iran has been described as "decisive" by the IAEA.
However, he put forward "new questions" which would he believed would be answered "in a short time." Iran, he said, was waiting to clear up certain "ambiguities" -- the argument used by Iranian officials to explain their reticence to accept stricter control over their nuclear program.
Iranian officials are keen to prevent the issue from being forwarded to the UN Security Council, which in turn could impose sanctions for non-compliance.
But several government officials have said Tehran will take every measure to avoid the Security Council.
President Mohammed Khatami declared Thursday that Iran "will continue its cooperation with IAEA despite the (its) inappropriate resolution."
Highly influential former president Ali Akbar Hachemi-Rafsanjani posed four conditions Friday on signing the additional protocol, including no inspections in non-nuclear military sites and places of worship.