"This is outrageous to us," Sharpton said.
"It's either a clear case of police abuse or racial profiling," he said. "This happens every day, but to have it happen to one of the most prominent black academicians is unbelievable."
This is the third incident in recent months in which blacks at Harvard have accused the school or police of heavy-handed treatment, though the two previous incidents were both on campus.
In February, a woman claimed that Harvard wrongly banned her from the school and barred her from attending graduation ceremonies after she was linked to the murder of a man on campus.
Chanequa Campbell said she was not making an "overall claim of racism," but "I do believe I am being singled out. ... The honest answer to that is that I'm black and I'm poor and I'm from New York and I walk a certain way and I keep my clothes a certain way," she said. "It's something that labels me as different from everyone else."
Prosecutors said Campbell invited the accused killer, a reputed marijuana dealer who was allegedly selling to students, into the dorm where the murder took place.
Months earlier, an African-American teenager, who was caught trying to sever a bike lock on the campus from what turned out to be his bicycle, claimed Harvard police screamed racial obscenities at him.
Gates has been a member of the Harvard faculty since 1991 and holds one of 20 "university professors" positions at the school. He also was named by Time magazine as one of the 25 most influential Americans in 1997.
"I was obviously very concerned when I learned on Thursday about the incident," Harvard president Drew Gilpin Faust said in a statement. "He and I spoke directly and I have asked him to keep me apprised."
The Associated Press contributed to this report.