Cook didn't give names, but his comments hinted at Facebook's Cambridge Analytica data scandal, where the firm improperly gained access to data from more than 50 million user profiles.
"We reject the notion that getting the most out of technology means trading away your right to privacy, so we choose a different path: collecting as little of your data as possible, and being thoughtful and respectful when it's in our care. Because we know it belongs to you," Cook said in his address at Duke University in Durham, North Carolina.
Cook, who has previously called data privacy a human right and a civil liberty, hasn't been shy about his criticism of Facebook. When asked in March how he would handle the situation if he was Facebook CEO Mark Zuckerberg, he told Recode's Kara Swisher and MSNBC's Chris Hayes that he "wouldn't be in this situation."
Cook also applauded the anti-sexual harassment movement, telling graduates to be fearless like the women who say "Me Too." The Apple chief also tipped his hat to survivors of the Parkland school shooting, and those who defend immigrant rights.
"It's in those truly trying moments that the fearless inspire us," Cook said. "Fearless like the students of Parkland, Florida, who refused to be silent about the epidemic of gun violence have rallied millions to their cause. Fearless like the women who say 'me too' and 'time's up.' Women who pass light into dark places and move us into a just and equal worker."
He added: "Duke graduates, be fearless. Be the last people to accept things as they are and the first ones to stand up and change them for the better."
Cook received his Master of Business Administration from Duke's Fuqua School of Business in 1988. He joined the university's board of trustees in 2015.