Plastic deformation of crystalline metals across various length scales is driven by the collective motion of defects such as dislocations, grain boundaries, and micro/nano-voids and their mutual interactions. To get a mechanistic understanding of plastic deformation mechanisms in crystalline metals at micron- and sub-micron length scale requires an integrated computational model which can capture both defect microstructure characteristics and the macroscopic constitutive behaviors of the materials. With this motivation, the defect dynamics element model (DDEM) has been developed to concurrently couple a dislocation dynamics (DD) modeling with finite element method (FEM). While the dynamics motion of dislocation and the generated plastic strain is captured by the DD framework, the FE simulation computes the stress field satisfying equilibrium conditions. In this study, we study mechanical behaviors of single-crystal Al micro-pillar embedded with nanovoids under uniaxial tension. The nano-porous pillar shows increasing strength with increasing void size and increasing strength with decreasing relative density of the pillar. For samples without existing dislocation, the void shape plays a significant role on the stress at which the dislocation nucleation occurs and consequently the overall response of the pillar. This multi-scale model shows good agreement with recent nano-characterization experiments.