The BSU at a Martin Luther King Day event Monday called for a higher enrollment of black students and made other demands, including more funding for the organization, the Detroit Free Press reported.
"They want special treatment and separate treatment based on their race," Gratz told the newspaper Tuesday. "That's something that the civil rights movement has fought against for decades."
Gratz sued the university in the 1990s after being rejected for admission at the Ann Arbor campus. The U.S. Supreme Court ruled in 2003 the university's policy of using a point system for admissions and assigning additional points to minority applicants was unconstitutional.
Gratz later spearheaded a drive for a Michigan referendum that said the state could not use racial consideration.
A video shows one student at the BSU event saying the group would use "physical actions" if its demands are not met. Gratz accused the BSU of threatening violence, but Geralyn Gaines, the BSU secretary, said any action taken would be non-violent.