The decision was welcomed by President Trump’s base of supporters, which has extolled his demands for stricter American immigration rules and a clampdown on refugees, as well as his promises to build a wall along the Mexico border.
Conservative websites that support Mr. Trump, which viewed the proposed migration pact as a threat to national security, prominently reported the news. “Breaking. U.S. Withdraws From Obama-Negotiated U.N. Agreement on Mass Migration,” read the headline on Redstate.com
The United States Mission said in its statement that it had informed Secretary General António Guterres that “the United States is ending its participation in the Global Compact on Migration.”
The United States has been part of the talks since they began in April, the outcome of a political declaration in New York by all 193 members of the United Nations last year in favor of protecting the rights of migrants and refugees by assuring their safe resettlement and access to employment and education.
The Obama administration was a strong advocate of the declaration, and Mr. Guterres has said he considers the agreement a major goal for 2018.
Mr. Trump’s United Nations ambassador, Nikki R. Haley, said in the statement announcing the withdrawal that the declaration contained “numerous provisions that are inconsistent with U.S. immigration and refugee policies and the Trump administration’s immigration principles.”
Ms. Haley, a child of Indian immigrants, emphasized in the statement that “America is proud of our immigrant heritage and our longstanding moral leadership in providing support to migrant and refugee populations across the globe.”
However, she said, “our decisions on immigration policies must always be made by Americans and Americans alone.”
The decision made migration the second major topic of a United Nations agreement to be repudiated by the Trump administration this year. Six months ago, it announced American withdrawal from the Paris Climate accord to combat global warming.
The Trump White House also has moved to distance itself from some key United Nations agencies over political issues, including Unesco — the United Nations Educational, Scientific and Cultural Organization — and the United Nations Population Fund, the world’s leading provider of family-planning services.
The migration announcement came two days before a United Nations conference on migration in Puerto Vallarta, Mexico, in which the United States had been expected to actively participate.
The announcement also came against the backdrop of growing migrant and refugee crises from wars, conflicts and deprivation that have afflicted the Middle East, Africa and parts of Asia.
Chaotic cross-border migration has provoked political backlashes in Europe and helped create booms in the smuggling and exploitation of migrants and refugees across the Mediterranean from Africa. Just last week, rights advocates expressed outrage at video showing African migrant men in Libya sold as slaves.
The United Nations has estimated that more than 60 million people have been displaced around the world, the largest figure since World War II.
Migrant-rights advocates expressed a mix of shock and bafflement at the Trump administration’s announcement, asserting that nothing proposed in the Global Compact would be mandatory. Some said the absence of the United States from the agreement could worsen the problems.
“An unwillingness even to negotiate international principles for safe, regular and orderly migration is a head-in-the-sand denial of a basic reality of human history,” said Bill Frelick, the refugee rights program coordinator at Human Rights Watch.
“Simplistic solutions like walls will not solve the complex problem of unsafe, irregular, disorderly migration, demonstrating a callous disregard for the lives of migrants and jaw-dropping irresponsibility toward the community of nations,” Mr. Frelick said.
Kevin Appleby, the international migration policy director at the Scalabrini International Migration Network, a New York-based advocacy group, said the Trump administration was “more interested in appeasing a small minority of Americans than working with the world on a pressing global issue.”