"Even if Trump himself is interested in negotiations, the people around him are committed to not letting that happen," said the president of the National Iranian American Council.
Secretary of State Mike Pompeo said on Sunday that President Donald Trump is "happy to talk with folks at any time."
Finance ministers of Germany, France and the U.K. have been working together to move the plan forward.
"The safety and security of U.S. citizens overseas is one of our highest priorities," a State Department official said.
Earlier in the week, reports claimed U.S. officials had sought to establish dialogue with Moscow ahead of the State Department's new sanctions.
"We deeply regret the re-imposition of sanctions by the U.S., due to the latter's withdrawal from the Joint Comprehensive Plan of Action," the foreign ministers of the EU, Germany, France and the U.K. said Monday.
U.S. Secretary of State Mike Pompeo has warned that North Korea's continued work on its weapons programs does not fit with its commitment to denuclearize.
During a hearing, Pompeo upheld the statement as an example of President Donald Trump's decisive foreign policy.
"If the current capabilities of the Revolutionary Guards ... reaches the ears of the adventure-seeking president of America, he will never make this kind of mistake."
Recent satellite images suggest North Korea may finally be moving to dismantle a test site but doubts and unclarity remain over how Kim intends to implement "denuclearization."
The two leaders began the day with a tête-à-tête—and are now in a bigger meeting with officials.
"Contrary to our military's suspension of joint Korea-U.S. military exercises, North Korea is conducting military exercises on a scale similar to previous years."
President Trump said last week that 200 "fallen heroes" had been sent back to the U.S., but Pompeo told Senate none had as yet been received.
Pompeo also said that America "will continue to help the world's most vulnerable refugees."