A (2 + 1)-dimensional multi-component derivative nonlinear Schrödinger (DNLS) equation is obtained from the symmetry constraint of the modified Kadomtsev-Petviashvili equation. The model is proved to be integrable under the meaning that it possesses the Painlevé property and the infinitely many generalized symmetries which constitute a generalized W_∞ algebra. An integrable DNLS hierarchy is obtained from the flow equation of infinitely many symmetries of the DNLS equation.