White House bureau chief Steve Herman contributed to this report.
Iran signaled Thursday that it was willing to take steps to reduce the tensions over its nuclear program with the Trump administration.
Iranian Foreign Minister Mohammad Javad Zarif told reporters in New York that Tehran would be open to more intrusive inspections of its nuclear program if Washington lifted its economic sanctions.
But the offer, which Zarif described as "a substantial move," was met with a tepid response.
A senior administration official told VOA on background, "The president has repeatedly said he is willing to have a conversation with Iranian leaders. If Iran wants to make a serious gesture, it should start by ending uranium enrichment immediately and having an actual decision-maker attempt to negotiate a deal that includes a permanent end to Iran's malign nuclear ambitions, including its development of nuclear-capable missiles."
The Trump administration has been tightening sanctions on Iran since the U.S. withdrew from the 2015 multilateral nuclear deal known as the Joint Comprehensive Program of Action.
Washington is trying to force Tehran to agree to stricter limits on its nuclear capacity, curb its ballistic missile program and end support for proxy forces in a regional power struggle with U.S.-backed Persian Gulf Arab states.
On Thursday, Zarif hinted at the steps Tehran was willing to take. Referring to its recent moves to escalate uranium enrichment, Zarif said they "could be reversed."
"It's not about photo ops. We are interested in substance," he said.
Fears of direct U.S.-Iranian conflict have risen since May, with several attacks on oil tankers in the Persian Gulf, Iran's downing of a U.S. surveillance drone, and a plan for U.S. airstrikes on Iran last month that President Donald Trump called off at the last minute.