"When Harvard University, to which the entire world looks for leadership, abandons its commitments to academic freedom and open and unfettered debate, it undermines its responsibilities and its opportunities," Sullivan said.
"Regrettably, Harvard's administrators acted in ways grossly antagonistic to the very norms that make Harvard the epitome of higher education."
Sullivan withdrew from Weinstein's defense team in May, saying that the new trial date would conflict with his teaching responsibilities. But he stood by his initial decision to join the team.
"In America everyone is entitled to a defense, in America everyone is presumed innocent until proven guilty, and in America everyone is entitled to due process of law under our Constitution," Sullivan said.
Harvard University told CNN that the decision not to reinstate Sullivan and Robinson as faculty deans was unrelated to Sullivan's role as Weinstein's attorney.
"As we have repeatedly stated, the decision not to renew Ronald Sullivan and Stephanie Robinson was not directly related to the Weinstein representation, but rather due to their failure to fulfill their responsibilities as Faculty Deans of Winthrop House," the university said in a statement to CNN.
Sullivan's decision made waves on campus
The couple were the first black faculty deans in Harvard's history. Harvard has 12 undergraduate houses, which are residential facilities that have their own dining halls, common rooms and other spaces for activities.
"Over the last few weeks, students and staff have continued to communicate concerns about the climate in Winthrop House to the college. The concerns expressed have been serious and numerous," Khurana wrote. "The actions that have been taken to improve the climate have been ineffective, and the noticeable lack of faculty dean presence during critical moments has further deteriorated the climate in the House."
Weinstein's trial begins later this year
Weinstein's trial is set to begin September 9.
The disgraced movie mogul is accused of raping a woman in a New York hotel room in 2013 and forcibly performing oral sex on another woman at his Manhattan apartment in 2006. The allegations against him and his resulting downfall helped launch the #MeToo movement.
The former film executive faces five felony charges: two counts of predatory sexual assault, one count of criminal sexual act in the first degree, and one count each of first-degree rape and third-degree rape. He has pleaded not guilty to all charges.
Weinstein has denied all accusations of nonconsensual sex.
CNN's Jason Hanna and Monica Haider contributed to this report.