The paper contributes to the problem of robotic manipulation where the interaction between robot and environment is an essential part of the task. In order to deal with impacts, oscillations and constrained motion, a model-based optimization approach is suggested, which relies on a detailed dynamic model of the manipulator incorporating finite gear stiffnesses and damping. These models are used to define an optimization problem, which is then solved using numerical programming methods. The intention of the proposed method is to provide a tool in the planning stage of an assembly task for an efficient manipulator optimization with respect to increased productivity and reliability. It is illustrated with an assembly task, namely inserting a rigid peg into a hole with a PUMA 562 manipulator. The robot's position and its control coefficients, which have a large influence on its dynamic response behavior, are adjusted according to the specific needs of the manipulation task to be carried out. The expected advantage in industrial applications is a comparatively easy implementation, because performance can be improved by simply adjusting "external" parameters as mating position and coefficients of the standard joint controller. Particularly, no modifications of the control architecture and no additional hardware are required. Application of the proposed approach to a rigid peg-in-hole insertion under practical constraints can reduce the measure for impact sensitivity by 17%, that for mating tolerances by 78% and the damping of end-effector oscillations and motor torques by up to 79%. These improvements are shown to be reproducible experimentally. The result is a planning tool, which allows any industrial robot to be optimized for the specific needs of any manipulation task.