The US Senate has passed a bill that would bar Iran's ambassador to the UN from entering the country.
The chamber voted unanimously on Monday to bar Hamid Aboutalebi, who was part of the Muslim student group that seized the US embassy in Tehran in 1979.
Fifty two Americans were held for 444 days during the crisis.
The BBC reports the House of Representatives is also expected to pass the measure barring him from entering the United States.
The Iranian foreign ministry is said to be in talks with US officials following President Hassan Rouhani's nomination of Mr Aboutalebi to the UN post.
Senator Ted Cruz (Republican, Texas) who introduced the legislation in the Senate, said the chamber "is not going to just ignore this most recent insult".
"This nomination is part of Iran's clear and consistent pattern of virulent anti-Americanism that has defined their foreign policy since 1979," he said.
In an interview with an Iranian news site, Mr Aboutalebi said he was not part of the group that took over US embassy and was only later asked to translate for the students.