SrTiO3 (STO) films are widely used as substrate of oxide devices. Although STO is one of the most studied materials, both experimentally and computationally, the effect of strain at the interface is almost completely ignored. In this work, we perform Density Functional Theory (DFT) calculations using the SCAN meta-GGA exchange-correlation functional to study the effect of uniaxial-and biaxial-strain on structural and electronic properties of STO interfaces. We find that under tensile uniaxial-strain, the band gap increases significantly, as a consequence of a large tilting in the octahedra. On the other side, under compression, the band gap is almost constant. Similar effects are seen for tensile biaxial strain, while for compressive strain, the gap first increases and then decreases, due to the temporary appearance of a polar distortion. In addition, we observe an orbital inversion at the conduction-band edge under different uni/bi-axial-strain conditions. This work provides a new perspective of the use of strain to modulate the structural and electronic properties of perovskite film materials for multiple applications.