Months of indirect talks between Tehran and Washington to salvage the nuclear accord with six major powers have stalled since September, with both sides accusing each other of making unreasonable demands.
Ayatollah Ali Khamenei's guarded approval comes days after both Tehran and Washington denied a report that they were nearing an interim deal under which Tehran would curb its nuclear programme in return for sanctions relief.
"There is nothing wrong with the agreement (with the West), but the infrastructure of our nuclear industry should not be touched," Khamenei said, according to state media.
A U.S. State Department spokesperson declined specific comment on Khamenei's remarks, reiterating the Biden administration stance that the United States "is committed to never allowing Iran to acquire a nuclear weapon."
"We believe diplomacy is the best way to achieve that goal on a verifiable and durable basis, but the President has also been clear that we have not removed any option from the table," he said, alluding to the possibility of military action.
"We will not characterize the nature of an Iranian leader's remarks," the spokesperson added.
The 2015 agreement limited Iran’s uranium enrichment activity to make it harder for Tehran to develop nuclear arms, in return for lifting international sanctions.
Then-U.S. President Donald Trump exited the pact in 2018 and reimposed sanctions that have crippled Iran's economy, leading Tehran to gradually move well beyond the deal's nuclear restrictions and reviving U.S., European and Israeli fears that Iran may seek an atomic bomb.
Echoing Iran's official stance for years, Khamenei said the Islamic Republic has never sought to build a nuclear bomb.
"Accusations about Tehran seeking nuclear weapons is a lie and they know it. We do not want nuclear arms because of our religious beliefs. Otherwise they (the West) would not have been able to stop it," Khamenei said.
Khamenei, who has the last say on all state matters, said the country's nuclear authorities should continue working with the U.N. nuclear watchdog "under the framework of safeguards."
However, Khamenei called on Iranian authorities not to yield to the International Atomic Energy Agency's (IAEA) "excessive and false demands," adding that a law passed by Iran's hardline parliament in 2020 had to be respected.
Under the law, Tehran would suspend IAEA inspections of its nuclear sites and step up uranium enrichment if sanctions are not lifted.
"This is a good law ... which must be respected and not violated in providing access and information (to the IAEA)," Khamenei said.
Last month, the IAEA reported limited progress over disputed issues with Iran, including re-installing some monitoring equipment originally put in place under the 2015 pact that Tehran ordered removed last year.
(Writing by Parisa Hafezi; Additional reporting by Arshad Mohammed in Saint Paul, Minn; Editing by Alex Richardson, David Holmes, Sharon Singleton and Mark Porter)
