Responding to a question at the regular noon briefing in New York, UN Deputy Spokesman Farhan Haq said the world body has a "standard policy" against the imposition of death penalty. Today's verdict will not make many in Pakistan happy.
Insulting the Prophet Muhammad is punishable by death under Pakistani law, and dozens have been killed following accusations, some by angry mobs.
Bibi's husband, Ashiq Masih, had returned from Britain with their children in mid-October and was waiting for her to join them, the brother added.
Mumtaz Qadri was hanged for the killing but has been hailed a martyr by hardliners. "I just don't know what to say, I am very happy, I can't believe it".
The court said: "The alleged extra-judicial confession was not voluntary but rather resulted out of coercion and undue pressure as the appellant was forcibly brought before the complainant in presence of a gathering, who were threatening to kill her; as such, it can not be made the basis of the conviction".
Two Muslim women refused to drink from a container used by a Christian, and a few days later, a mob accused her of blasphemy. The following year she was sentenced to death.
Bibi's husband Ashiq Masih has reached Pakistan along with his family from the United Kingdom to shift her overseas, The News reported quoting sources.
Protests were staged in major cities across Pakistan with club-wielding demonstrators blocking Islamabad's main highway and barricading roads in Karachi and Lahore.
The federal government on Thursday made a decision to deal with the crisis, arising out of Asia Bibi's acquittal in blasphemy case, in a peaceful manner, ARY News reported.
Chief Justice Saqib Nasir, who headed a special three-person bench set up for the appeal, cited the Koran in his ruling, writing "Tolerance is the basic principle of Islam" and noting the religion condemns injustice and oppression.
After the verdict was delivered, demonstrations against it were reported in Karachi, Lahore, Peshawar and Multan.
Thousands of supporters of the Tehreek-e-Labbaik party, led by firebrand cleric Khadim Hussain Rizvi, took to the streets in protests, demanding Bibi's public execution. Addressing the crowd, another leader of the group, Pir Mohammad Afzal Qadri, issued an edict that all three Supreme Court judges who passed the verdict should be killed.
The case has divided Pakistan, where two politicians who sought to help Bibi were assassinated, and outraged Christians worldwide, with Pope Francis saying he personally prayed for Bibi.
The acquittal immediately raised fears of religious violence and presented a challenge to the government of new Prime Minister Imran Khan, who warned Islamist protesters on Wednesday night not to "test the patience of the state".
What is blasphemy in Pakistan?
"The verdict has shown that the poor, the minorities and the lowest segments of society can get justice in this country despite its shortcomings", Bibi's lawyer Saif-ul-Mulook told AFP. "Pakistan's Supreme Court must be appreciated that it upheld the law of the land and didn't succumb to any pressure".