WASHINGTON, April 15 (Xinhua) -- The United States insisted on Tuesday that it will not issue a visa to Iran's new ambassador to the United Nations Hamid Aboutalebi for his role in the 1979 hostage crisis.

"What we have told the United Nations and the Iranian government is that we will not grant this visa," State Department spokeswoman Jennifer Psaki said at a regular press briefing. "That has not changed."

"Given his role in the events of 1979, which clearly matter profoundly to the American people, it would be unacceptable for the United States to grant this visa," she added.

The White House said on Friday that it had informed Tehran of its visa denial to Aboutalebi, as both chambers of U.S. Congress had adopted legislation calling for the ban.

Iran responded by announcing on Monday that it would sue the United States over the matter. The Islamic republic also said that it has a number of options to take against Washington's move.

Aboutalebi said he was only an interpreter for the militant group that seized the U.S. embassy in Tehran on Nov. 4, 1979 and held 52 Americans hostage for 444 days.

Iran said it has no replacement for Aboutalebi, who has served as Iran's ambassador to Australia, the European Union, Belgium, and Italy.

The UN on Monday called the confrontation "a very serious issue. "