Ramin Mehmanparast made the comment a day after the six powers met to discuss prospects of further sanctions against Iran over its nuclear program, with participants saying China made clear it opposed more punitive action at the moment.
Iran's official IRNA news agency said Mehmanparast described the powers' failure to reach an agreement on Iran's nuclear issue as natural.
Diplomats from the United States, Britain, France, Germany, Russia and China held a three-hour meeting in New York on Saturday.
It came after Iran ignored U.S. President Barack Obama's Dec 31, 2009, deadline to respond to an offer from the six powers of economic and political incentives in exchange for halting its nuclear enrichment activities.
The solution lies in the recognition of Iran's nuclear rights by the group, Mehmanparast said. The planned meetings of the (six powers) would not have clear results as long as they lack a realistic approach.
Washington and its Western allies accuse Iran of trying to develop nuclear weapons under the cover of its civilian atomic program. Iran, the world's fifth-largest crude exporter, says its program is designed to generate electricity.
The European Union, which hosted the meeting at its New York office, said that despite the lack of a concrete outcome, further sanctions were now on the big-power agenda and the six would be in contact again soon to continue the discussions.
All the powers except China sent top level Foreign Ministry officials to Saturday's meeting. But Beijing, which said earlier this month that it was not the right time for new sanctions, sent only a mid-ranking diplomat from its U.N. mission.
China's virtual snub of the meeting dismayed the four Western powers in the group. They had hoped to reach an agreement on whether to begin drafting a new U.N. Security Council resolution on a fourth round of sanctions against Iran.
Three previous rounds of U.N. sanctions have targeted Iran's nuclear and missile industries, but Iran has shrugged them off and said it plans to pursue its right to enrich uranium, which can have both civilian and military uses.
The Western powers had originally hoped to sanction Iran's energy sector but dropped the idea months ago when it became clear Russia and China would never accept it.
(Reporting by Hashem Kalantari; writing by Fredrik Dahl; editing by Philippa Fletcher)