(Adds background on U.S. ability to deny visas to diplomats, Iranian comment, paragraphs 6 and 12)
WASHINGTON, April 8 (Reuters) - The White House made clear on Tuesday that it did not welcome Iran's choice of Hamid Abutalebi as its new United Nations ambassador, saying officials had told Tehran that the selection was "not viable."
But White House spokesman Jay Carney stopped short of saying Abutalebi would be barred from entering the United States because of his alleged role in the 1979-1981 hostage crisis, during which radical Iranian students held U.S. Embassy staff for 444 days.
"We've informed the government of Iran that this potential selection is not viable," Carney told reporters.
Asked to explain what "not viable" meant, Carney said: "It's diplomatic jargon to mean what you want it to mean."
He declined to elaborate on whether Abutalebi would be barred from the country, and emphasized that Iran's choice of Abutalebi was a "potential selection" that had "not been formally made."
As the "host" nation for the U.N. headquarters, the United States is generally required to provide access to the United Nations for foreign diplomats. However, the State Department last week said U.S. law allows it to deny visas to diplomats for reasons of "security, terrorism, and foreign policy."
Earlier on Tuesday, Iran's Foreign Ministry played down legislation passed by the U.S. Senate on Monday to bar Abutalebi from entering the United States, saying it had contacted the U.S. government about a visa.
Some members of the U.S. Congress have expressed outrage at the choice of the veteran Iranian diplomat. The House of Representatives is expected to soon pass a similar ban.
"We share the Senate's concerns regarding this case and find the potential nomination very troubling," said Carney.
In remarks to Iranian media, Abutalebi has played down his role during the hostage crisis, suggesting he was just a translator.
It was unclear whether the dispute over the ambassador would have an impact on a new round of talks about Iran's nuclear program that began on Tuesday in Vienna between Iran and six major world powers, including the United States.
"It has been a usual practice in the Iranian Foreign Ministry to formally appoint ambassadors for all foreign postings, once all formalities pertaining to this process are completed," a spokesman for Iran's U.N. mission in New York said on Tuesday. (Reporting by Steve Holland and Roberta Rampton; Editing by Sandra Maler, David Storey and Mohammad Zargham)