Iranian supreme leader says no negotiations 'on any level' with US
Ties between Washington and Tehran have deteriorated since the US pulled out of the 2015 nuclear deal between Iran and major powers.
The international deal aimed to curb Iran's uranium production.
On Monday, US President Donald Trump said he believed Iran was likely behind the attacks on key Saudi oil refineries at the weekend that sent oil prices soaring.
If the US "takes back its words and repents and returns to the nuclear deal, which they have violated, they can take part in the meetings of signatories to this agreement with Iran," Khamenei said.
"Otherwise, no negotiation on any level will happen between officials of the Islamic Republic and the US, neither in New York nor anywhere else," he said on state television.
There had been speculation over a possible meeting between Trump and Iranian President Hassan Rowhani on the sidelines of the UN General Assembly in New York, which begins this week.
Trump on Monday did not rule out a meeting, saying that he had "no meeting scheduled" with the Iranian president but adding: "I know they want to meet."
NATO's secretary general said on Tuesday that the defence alliance was monitoring current events with concern after the Saudi oil refinery attacks.
"Any disruption to global energy supplies is clearly of concern to NATO allies," Jens Stoltenberg told dpa.
"I urge all parties to prevent further such incidents, which pose a serious threat to regional security," he added.
US Energy Secretary Rick Perry, however, downplayed the risk of an oil price shock, stressing that the world had hundreds of millions of barrels in oil reserves.
"This is a really large reserve," he said. "This market is substantially more elastic, more flexible and more resilient" than a decade ago, he said.
Oil prices eased only slightly on Tuesday after the previous day's price shock that was triggered by the Saudi attacks.
European Brent oil traded at 68.71 dollars per barrel on Tuesday morning, down 0.31 dollars from the previous day.
The US benchmark brand West Texas Intermediate stood at 62.34 dollars, which was 0.56 dollars less than on Monday.
