"If this propaganda is effective, the talks will fail and these countries will be back to square one," Alaeddin Borujerdi, the head of parliament's national security and foreign policy commission, told Mehr news agency.
He also said Iran "will not accept any new conditions in the nuclear issue" ahead of talks due to be held between Iran and six global powers in Geneva on Thursday.
Earlier on Monday Iran reiterated that its newly disclosed second uranium enrichment plant does not violate international law and said that concerns raised by the West were baseless.
"It does not violate any international law. Western countries are making unrealistic comments," foreign ministry spokesman Hassan Ghashghavi told reporters.
On Friday, the International Atomic Energy Agency (IAEA) announced that Tehran had told it the Islamic republic was building a second uranium enrichment plant in addition to its existing facility at Natanz.
The revelation unleashed a global outcry against Tehran which is already at loggerheads with world powers over its controversial atomic programme.
"The allegations… the media hype is baseless," Ghashghavi said, referring to the outrage expressed by Western leaders including US President Barack Obama.
He said Iran was "prepared to clarify all aspects of the new nuclear plant."
The new enrichment facility is being constructed south of Tehran on the road to the holy city of Qom.
On Sunday, Iran's nuclear chief Ali Akbar Salehi vowed that Tehran will stick to enriching uranium up to the five percent level — much lower than bomb-grade requirement, suggesting Tehran's atomic drive had peaceful aims.
Uranium enrichment lies at the centre of fears over Iran's controversial atomic work since the process to make nuclear fuel can also be used to make the fissile core of an atom bomb in much higher purifications of over 90 percent.
But US Secretary of State Hillary Clinton, in an interview with CBS network, said "we don't believe that they can present convincing evidence that it's only for peaceful purposes, but we are going to put them to the test on October 1."
Global powers suspect Tehran's nuclear drive is aimed at making nuclear weapons. Tehran denies the charge.
