IRAN'S supreme leader has warned there were limits to any concessions on its nuclear programme it would make for an easing of sanctions.
H blasted Israel as being "the rabid dog" of the region, bent on attacking Iran's reputation.
Mr Khamenei, speaking before a paramilitary group in Tehran, aimed to placate hardliners and show his backing for the Iranian officials preparing to meet with international negotiators.
Western diplomats reported progress during a previous round of talks in Geneva. They now hope to reach an accord that would halt Iran's nuclear efforts while negotiators pursue a more comprehensive agreement that would ensure it is solely for civilian purposes. Iran would get some sanctions relief under such a first-step deal, without any easing of the most harsh measures - those crippling its ability to sell oil, its main revenue maker.
Iran has suggested it could curb its highest-known level of uranium enrichment in a possible deal.
But Iranian leaders have made clear that their country will not consider giving up its ability to make nuclear fuel - the centrepiece of the talks since the same process used to make reactor stock can be used to make weapons-grade material.
Mr Khamenei said he would not "interfere in the details of the talks" - a clear nod of support for the government of Iranian president Hassan Rouhani, which has opened historic exchanges with the US. However he also said the main goal of the talks is the "stabilisation of the rights of the Iranian nation, including nuclear rights."
"There are red lines. There are limits. These limits must be observed," he said. "We have told the authorities, and they are required to observe the limits and should not fear the blusters of the enemies and opponents."
He also blasted what he called the US government's "warmongering" policies, including threats of military action, and he said sanctions cannot force unwanted concessions by Iran. At the same time, he said his country has "no animosity'" toward the American people and seeks "friendly" relations.
His complex message reflected Iran's internal divisions over the nuclear talks and outreach to the United States, which broke ties with Iran after hostage-takers stormed the U.S. Embassy compound in Tehran in 1979 the wake of the Islamic Revolution.
President Barack Obama also faces opposition to a deal from Israel, Saudi Arabia and critics in Congress, who say an first-step deal would give Iran too much in the way of sanctions relief for too little concessions. They also argue that Iran can't be trusted.