A theoretical model for the neoclassical toroidal plasma viscosity for tokamaks resulting from the symmetry breaking magnetic field perturbation caused by the collisionless detrapping/retrapping mechanism is presented. The results of the model are valid when the width of the collisional boundary layer is narrower than the width of the layer of the detrapping/retrapping process in the pitch angle space, and when the normalized magnitude of the perturbed magnetic field is much smaller than the inverse aspect ratio. The neoclassical toroidal plasma viscosity derived from this model scales with the collision frequency. The results can be used in modeling plasma rotation when the toroidal symmetry of |B| of the tokamaks is broken. Here, B is the magnetic field.