TEHRAN - The Islamic republic is not optimistic about the ongoing nuclear talks with the major powers, Iran's Supreme Leader Ayatollah Ali Khamenei said on Sunday.

"As I have said earlier in Mashhad (city), I am not optimistic about the nuclear talks," said Khamenei, adding that "But, with God's help, we will not suffer loss in the negotiations and this is an experience which will enhance the mental capacity of our nation."

Talking to a group of students one day ahead of the anniversary of the US embassy seizure in Tehran in 1979, he was quoted as saying by the official IRNA news agency that "Nobody should think of our (nuclear) negotiating team as compromisers. They... are on a hard mission and nobody should weaken" their position.

Iran and the P5+1 countries -- the United States, China, Russia, France and Britain plus Germany -- held a fresh round of talks in Geneva on October 15-16 and agreed to meet again in the Swiss city on November 7-8.

"If the negotiations bear fruits, so much the better. But, if there is no result, it means that the country should rely on itself," said the Iranian supreme leader.

The Iranian supreme leader reiterated earlier position of Iran' s high-ranking officials toward the United States, calling it the "enemy" of the Islamic republic and that the United States "cannot be trusted."

"We should not trust the enemy who smiles. The Americans, on the one hand, smile and express their willingness for negotiations and, on the other, they immediately say that they have all options on the table," he was quoted as saying.

"Well, what a damn thing they might do" against Iran, said Khamenei alluding to the military threats against the country's nuclear establishments by the United States and Israel.

"The United States is more on the side of the Zionists (Israel) and has to consider them," he said, emphasizing that "As we have said from the very beginning, we consider the Zionist regime as illegitimate."