Addressing a large and fervent congregation of the people on Tehran University campus on Friday, Ayatollah Movahedi Kermani said, "If you respect the redlines in the negotiations with the other side, you will surely have the support of Iran's Supreme Leader and all Iranians."
"We remind the Iranian negotiators that the US is enemy and you have to believe that only animosity is expected from the enemy, he added.
Iran and its negotiating partners are currently in talks to iron out differences and achieve a permanent comprehensive deal.
The two sides sealed an interim deal in Geneva, Switzerland, last November. The accord took effect in January and extended until November 24, 2014.
In July, after a meeting with EU Foreign Policy Chief Catherine Ashton, Iranian Foreign Minister Mohammad Javad Zarif told reporters that a common understanding is needed for the nuclear negotiations to bear fruit.
The Iranian foreign minister urged the West to seize the current opportunity to reach a final agreement with Iran.
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