"The will of the Iranian people is firm and will continue to follow the principles defined by the supreme guide [Ayatollah Ali Khamenei]," Elham said.
"Iran insists on negotiations while respecting its rights and avoiding any loss of international rights."
Iran delivered its response to the package drawn up by the six world powers, which offered technological assistance and negotiations if Iran suspended uranium enrichment, to Javier Solana, the EU foreign police chief.
Elham said his country was prepared to hold talks "especially with the 5+1 Group" of the permanent UN Security Council members plus Germany "on the common points in the Iranian package and the offer of the world powers".
Saeed Jalili, Iran's senior nuclear negotiator, said his country had submitted a "constructive and creative" response with "a focus on common ground," but he did not elaborate on the contents.
There has been considerable speculation in recent days that Tehran was softening its tone on the nuclear standoff, although the international community has made negotiations conditional on enrichment suspension.
Diplomatic sources said Solana has not ruled out a period of pre-negotiations during which world powers would refrain from new sanctions provided Iran did not start operating any more centrifuges to enrich uranium.
An interview with Ali Akbar Velayati, the foreign policy advisor to Khamenei, sparked hope in some quarters that Iran was on the verge of accepting the international proposal.
"Those who are agitating against our interests want us to reject the offer. As a consequence, it is in our interests to accept it," Velayati said.
But the government spokesman, questioned on Velayati's statement, said Iran's position had not changed.
"People are free to express their personal point of view. But it is the government which has the responsibility and decides ... in line with the principles defined by the supreme guide," Elham said.
Velayati himself has told state television that he was referring to negotiations rather than acceptance of the international offer.