Shear behavior and the failure modes of shear stressed masonry walls have been the subject of many investigations. In the present paper, the performance of an interface elasto-plastic constitutive model for the analysis of unreinforced masonry walls by means of micro-finite element modeling is evaluated. The micro-model is utilized to obtain the behavior of unreinforced masonry walls, based on assumption that the masonry bricks, mortar and their interface are three separate elements. In the present modeling, the behavior of bricks and mortar is assumed to comply with the plastic-damage model which is based on multiple damage variables. The behavior of the interface element is assumed to comply with the coulomb friction model having a limit on the critical shear stresses. A nonlinear analysis is performed by the application of explicit formulae in which displacements and rotations between bricks are taken into consideration. To validate the model, experimental results of masonry elements and walls is compared with the results obtained from the numerical analysis. It is concluded that the suggested model is suitable for assessing the behavior of masonry walls under vertical and horizontal loading.