President Obama on Friday signed into law legislation to bar United Nations ambassadors suspected of terror ties from receiving U.S. visas, but added that he would treat the law as “advisory,” arguing that it undercut his constitutional powers.

The bill, S. 2195, passed Congress earlier this month after lawmakers raised concerns about Iran's new envoy to the UN, Hamid Abutalebi, who is believed to have been a member of the group of Iranian students who stormed the U.S. embassy in Tehran in 1979, taking a number of American citizens hostage.

The White House, in a statement, said the measure would amend section 407 of the Foreign Relations Authorization Act to “deny admission to the United States to any representative to the United Nations who the President determines has been engaged in terrorist activity against the United States or its allies and may pose a threat to U.S. national security interests.”

In a signing statement, Obama cited former President George H.W. Bush in explaining his concerns about the law.

“As President Bush observed in signing the Foreign Relations Authorization Act, Fiscal Years 1990 and 1991, this provision ‘could constrain the exercise of my exclusive constitutional authority to receive within the United States certain foreign ambassadors to the United Nations,’" said Obama.

“Acts of espionage and terrorism against the United States and our allies are unquestionably problems of the utmost gravity, and I share the Congress's concern that individuals who have engaged in such activity may use the cover of diplomacy to gain access to our Nation,” he continued. “Nevertheless, as President Bush also observed, ‘curtailing by statute my constitutional discretion to receive or reject ambassadors is neither a permissible nor a practical solution.’

“I shall therefore continue to treat section 407, as originally enacted and as amended by S. 2195, as advisory in circumstances in which it would interfere with the exercise of this discretion,” Obama added.

Abutalebi’s appointment to Iran’s top UN post in New York City sparked outrage on Capitol Hill and calls for him to be barred entry into the U.S.

The White House earlier this month said that they would not grant Abutalebi a visa, calling his selection “not viable.”

The standoff over Iran’s UN envoy comes as the two nations and other world power continue negotiations over Tehran’s nuclear program.

White House press secretary Jay Carney, though, said last week that he did not believe that the dispute would affect those talks.