Yes. Once in Cuba, the airport, tourist hotels, banks, and CADECA bureaus can exchange currency (US and Canadian dollars, Euros, British pounds, etc.) for you. Hotels are often the most convenient place to make currency exchanges. Be sure to have proper ID (passport) on hand.
Do not accept offers to exchange currency from anyone who approaches you on the street. It is illegal and a common scam practiced all over the world to take advantage of travelers, who are unfamiliar with new currencies. This is particularly applicable, due to the dual currency system used in Cuba.