Iran's supreme leader has said talking to the US about his country's nuclear activities would hold no benefits, according to Iranian state television.
Ayatollah Khamenei restated Iran's right to nuclear technology
Ayatollah Ali Khamenei said Iran was ready to ease concerns over its uranium enrichment but would not suspend it.
"Negotiations with the United States are of no use for us. We have no use for such negotiations." he said.
Washington has said it will join EU states in talks with Iran if Tehran agrees to halt uranium enrichment.
"We will not negotiate with anyone over the undeniable right of nuclear technology and using it," said Ayatollah Khamenei.
"If they recognise this right, we are ready to negotiate over supervision controls," he added.
Waiting for response
The suspension of uranium enrichment is the key demand in a proposal aimed at resolving the nuclear row, backed by six world powers.
The UN has offered Iran a package of incentives, but Iran has so far not responded.
Last week Iran's president said a reply would come on 22 August.
The US believes Iran is trying to make nuclear weapons, but Tehran says it is enriching uranium for energy purposes, as it is entitled to under the terms of the nuclear Non-Proliferation Treaty, to which it is a signatory.