"We are heartbroken for the French people and those around the world for whom Notre Dame is a symbol of hope," Cook wrote on Twitter. "Relieved that everyone is safe. Apple will be donating to the rebuilding efforts to help restore Notre Dame's precious heritage for future."
He didn't elaborate on how much Apple (AAPL) is planning to donate. The company did not immediately respond to a request for comment.
The billionaires behind luxury giants LVMH Group, Kering and L'Oreal on Tuesday promised a total of €500 million ($565 million).
Meanwhile, French oil and gas company Total will give €100 million ($113 million), while consulting firm Capgemini committed €1 million ($1.1 million).
Monday's fire devastated large parts of the cathedral, including its iconic spire. The blaze was extinguished after nine hours.
CNN Business' Julia Horowitz contributed reporting.