According to the Los Angeles Times, the grants are worth nearly $200 million.
UCLA Chancellor Julio Frenk addressed the freeze in a letter Thursday.
"UCLA received a notice that the federal government, through its control of the National Science Foundation (NSF), the National Institutes of Health (NIH) and other agencies, is suspending certain research funding to UCLA," Frenk said.
"This is not only a loss to the researchers who rely on critical grants. It is a loss for Americans across the nation whose work, health, and future depend on the groundbreaking work we do."
News of the federal grants being suspended comes on the same week UCLA agreed to settle a $6 million lawsuit that claimed the university allowed pro-Palestinian protesters to block Jewish students on campus during demonstrations last year.
On Tuesday, the Trump administration also announced the U.S. Department of Justice's Civil Rights Division found UCLA violated the Equal Protection Clause of the Fourteenth Amendment and Title VI of the Civil Rights Act of 1964, "by acting with deliberate indifference in creating a hostile educational environment for Jewish and Israeli students."
"This disgusting breach of civil rights against students will not stand: DOJ will force UCLA to pay a heavy price for putting Jewish Americans at risk and continue our ongoing investigations into other campuses in the UC system," Attorney General Pam Bondi said in a statement.
Frenk said the federal government's decision "does nothing to address any alleged discrimination."
His letter also addressed the DOJ's allegations of antisemitism.
"We share the goal of eradicating antisemitism across society. Antisemitism has no place on our campus, nor does any form of discrimination," he wrote. "We recognize that we can improve, and I am committed to doing so.
"Confronting the scourge of antisemitism effectively calls for thoughtfulness, commitment, and sustained effort - and UCLA has taken robust actions to make our campus a safe and welcoming environment for all students."
In his letter, Frenk added that the leadership team at UCLA had been preparing for this for several months and have also developed contingency plans.
Meantime, Gov. Gavin Newsom said freezing research funding for UCLA makes the country less safe.
"It is a cruel manipulation to use Jewish students' real concerns about Antisemitism on campus as an excuse to cut millions of dollars in grants that were being used to make all Americans safer and healthier," said Newsom. "This is the action of a president who doesn't care about students, Californians, or Americans who don't comply with his MAGA ways."
The Associated Press contributed to this report.