The government said the Citizenship law will protect minorities from Bangladesh, Pakistan and Afghanistan
The United Nations human rights office voiced concern on Friday that India's new citizenship law is "fundamentally discriminatory in nature" by excluding Muslims and called for it to be reviewed.
Violent clashes erupted in Delhi between police and thousands of university students on Friday protesting the enactment of the contentious new law.
The government has said the Citizenship Amendment Bill, approved by parliament on Wednesday, was meant to protect minorities from Bangladesh, Pakistan and Afghanistan.
"We are concerned that India's new Citizenship (Amendment) Act 2019 is fundamentally discriminatory in nature," UN human rights spokesman Jeremy Laurence told a Geneva news briefing.
The new law does not extend the same protection to Muslim migrants as to six other religious minorities fleeing persecution, thereby undermining India's commitment to equality before the law, enshrined in its constitution, he said.
"We understand the new law will be reviewed by the Supreme Court of India and hope it will consider carefully the compatibility of the law with India's international human rights obligations," Laurence said.