"They are not after genuine and fair negotiations. Rather, that they are pursuing the goal of making the Iranian nation surrender."
Analysts have suggested it may be difficult for the Iranian delegation to agree to any substantial compromise since Iran is gearing up to elect a new president in June.
Asked about this theory, the U.S. official told journalists elections "may constrain their political space."
But, the official added, "when it comes to the nuclear file, the decisions rest in the hand of the supreme leader and he is not going to change in June."