'Only 12% of United Nations member states allow same-sex marriage, ' she wrote on Twitter. The latest policy change, the United States explained in the note, was aimed at ensuring all couples were treated equally.
The new policy went into effect on Monday.
"The Department of State will not issue a G-4 visa for same-sex domestic partners", a State Department memo reads. "In light of the landmark 2015 Supreme Court decision legalizing same-sex marriage, the USA extends diplomatic visas only to married spouses of US diplomats".
The policy backtracks a 2009 guidance from former Secretary of State Hillary Clinton, which extended diplomatic visas to domestic partners of domestic and worldwide diplomats. He warned that some could be vulnerable to prosecution, and that it will create hurdles for couples considering a posting at United Nations headquarters in NY.
A U.S. official said that some 105 families now residing in America would be impacted. But officials posted to global organizations, such as the United Nations, do not represent a foreign government, and there are no exceptions to the policy. However, that number may not take into account how many foreign nationals will not be able to apply for visas in the future.
Ms Kumar said there are documented cases of death threats being sent to same-sex partners and their families who decide to marry overseas when the act is illegal in their home country.
"Requiring a marriage as proof of bona fide partnership is a bad and cruel policy, one that replicates the awful discrimination many LGBT people face in their own countries". That's the current rule for heterosexual partners.
"Those not yet in the country will need to show they're married to secure a visa, potentially forcing those living in countries without marriage equality to choose between a posting at the United Nations headquarters or family separation", Akshaya Kumar of Human Rights Watch said in a blog post.
The policy was made effective Monday and comes despite the fact that the majority of countries around the world do not recognize same-sex marriage.
However, there are concerns about the implications of the new requirements for diplomats from countries which do not recognise same-sex marriages.
"This administration is becoming quite adept at family separation", he added. As of today, domestic partners of diplomats and United Nations officials based overseas will need to show they are married in order to enter the country on a diplomatic visa.
Farhan Haq, deputy spokesman for the U.N. Secretary General, told CBS News, "We are in touch with the authorities on this".