We consider an optimal control problem for an impulsive hybrid dynamic system, where jumps of a trajectory may occur only at the moments of hitting a given closed set. A time reparameterization technique is applied to reduce the original problem to the one with bounded controls. We show that the reparameterized problem is equivalent to optimization in a class of generalized solutions to the impulsive hybrid system. Necessary conditions for optimality of generalized control processes are obtained by interpreting the Maximum Principle in the reduced problem.