Congress has unanimously passed a bill that would bar Iran's pick for ambassador to the UN from entering the United States. The Senate also unanimously approved the measure two days before.
Hamid Aboutalebi was a part of a student group that seized the US embassy in Tehran in 1979. Fifty two Americans were held for 444 days.
The BBC reports the White House has told Iran Mr Aboutalebi was "not viable".
Mr Aboutalebi has previously served as Iran's ambassador to Belgium, the European Union, Italy and Australia.
In an interview with an Iranian news site, Mr Aboutalebi said he was not part of the group that took over the US embassy and was only later asked to translate for the students.