(CNN) -- A senior Iranian official said Saturday that Tehran is not considering a replacement for Hamid Aboutalebi, its choice for ambassador to the United Nations, despite the United States denying him a visa, Iranian state TV reported.
The United States has told Iran that it will not issue a visa to Aboutalebi because of his ties to the 1979 takeover of the U.S. Embassy in Tehran, the White House said.
But Iran's Deputy Foreign Minister Abbas Araghchi told reporters in Tehran that Aboutalebi remained Iran's choice and that it is following up on the issue through diplomatic channels, according to state broadcaster Press TV.
Iranian lawmaker Hossein Naqavi Hosseini told state news agency IRNA that the United States was obliged to honor its responsibility to issue visas in its role as host for the United Nations headquarters in New York.
The White House is still reviewing a bill passed in Congress this week prohibiting the ambassador from entering the United States.
Aboutalebi was a member of the Muslim Students Following the Imam's Line, the group of militants that seized the embassy on November 4, 1979, holding 52 Americans hostage for 444 days.
He is a veteran diplomat who has served as Iran's ambassador to Australia, Belgium, Italy and the European Union. He has also held high-profile posts in the Iranian Foreign Ministry.
He currently works in the political affairs office of President Hassan Rouhani and is believed to be close to the Iranian leader, who is widely viewed as a moderate with a reformist agenda.
In an interview with Iranian media, Aboutalebi said he served as translator and negotiator, but denied taking part in the initial occupation of the embassy.
One of the leaders of the takeover of the U.S. Embassy, Abbas Abdi, told CNN exclusively from Tehran that "Mr. Aboutalebi was not in Tehran during the initial invasion."
Abdi, currently a reformist journalist, said Aboutalebi has "no relation to the decision-making team, the group who invaded and those who continued the hostage captivity in Iran."
The choice of Aboutalebi could complicate U.S. President Barack Obama's efforts to re-engage with Tehran after the election of Rouhani and negotiate a comprehensive agreement with five other world powers to curb Iran's nuclear program.
Asked Friday if the issue over Aboutalebi would affect nuclear talks, U.S. State Department spokeswoman Jen Psaki told reporters it had not impacted discussions held this week.
She declined to give details of the reasons behind the visa refusal but said the United States had been "very clear ... with the Iranians that this nomination is not viable."
Hamid Babaei, a spokesman for the Iranian mission to the United Nations, said it was a "regrettable decision" by the United States which was "in contravention of international law, the obligation of the host country and the inherent right of sovereign member states to designate their representatives to the United Nations."
With no formal relations between the United States and Iran, the U.N. mission is Tehran's only diplomatic operation in the United States and has played a role in facilitating unofficial exchanges of messages between the two nations.
The step taken this week is unusual, given that the United States is obligated to grant entry visas to representatives of U.N. member states, in accordance with a 1947 agreement signed with the world body.
CNN's Laura Bernardini, Elise Labott and Richard Roth contributed to this report.