US officials described the intercept by the SU-27 jet on Wednesday as "dangerous and unprofessional".
Russia's defence ministry said the US plane had been approaching Russian territory and the SU-27 pilots had adhered to international rules.
Russia is currently carrying out military exercises in the Black Sea.
Pentagon spokesman Capt Jeff Davis said the US Navy P-8A Poseidon aircraft had been conducting routine operations in international airspace when the Russian fighter made the unsafe manoeuvre.