This research attempts to investigate the effect of soil-structure interaction (SSI) on the seismic response of buildings. Computational simulation of a one storey building having different natural periods is performed using time history analysis. Different earthquake motions with different peak ground accelerations (PGA) levels are used as excitations. The ground motion records have been selected in order to ensure low, moderate, and high PGA levels. Moreover, sandy soil with several values of shear wave velocities is used in order to investigate the sensitivity of the seismic response to the velocity variation. An efficient discrete-element model which represents the rotational and horizontal degrees of freedom of the soil mass is considered in the analysis. The coupled equations of motion for the building model with SSI are presented and solved in incremental form using the Newmark's step by step iteration method. In general, the results of the study in terms of response, peak response and peak response amplification show significant changes in considering and ignoring SSI effect. In particular, the numbers of significant cycles of large response amplitude for the building have been increased due to the inclusion of SSI. Moreover, considering the soil flexibility amplifies the peak response of buildings with low natural periods. Furthermore, it has been found that, shear wave velocity variation shows appreciable changes in the peak dynamic response amplification and seems to be insignificant at high natural periods for all levels of earthquake excitations considered.