Most of the ancient European structures consist of unreinforced masonry. This composite material is characterized by a highly asymmetric behaviour in tension and compression. For this reason, masonry structures were usually designed to work in compression, resulting particularly vulnerable to loads, such as seismic loads or differential settlements, which introduce tensile actions in the masonry elements. Therefore, the accurate assessment and prediction of the structural response of masonry is crucial for the preservation of our architectural heritage. Among the variety of modelling approaches used for studying the response of masonry structures, simplified micromodels lump the nonlinearities of the system in pre-defined weak planes—usually corresponding with the position of the mortar joints—by introducing nonlinear zero-thickness interfaces among elastic bricks with expanded geometry. With this approach, different local failure mechanisms of masonry can be described in an accurate manner while retaining computational efficiency. In this work, an extension of an interface material model for the description of the response of masonry under cyclic loading is proposed. The original model accounts for mixed-mode fracture in tension-shear and cohesion and friction in compression-shear. In this contribution, the model is enhanced with a plastic-damage cap to phenomenologically describe the crushing failure mechanism of masonry. The improved interface material model is used within a simplified micromodelling approach to capture the in-plane behaviour of masonry walls subjected to non-proportional loading. The capabilities and limitations of the model to capture the interaction between various nonlinear phenomena (damage, friction, plasticity) are discussed.