Motivated by an experimental report of iridate superlattices, we performed first-principle electronic structure calculations for SrIrO3/SrTiO3. Heterostructuring causes SrIrO3 to become Sr2IrO4-like, and the system has the well-defined j(eff) = 1/2 states near the Fermi level as well as a canted antiferromagnetic order within the quasi-two-dimensional IrO2 plane. In response to a larger tensile strain, the band gap is increased due to the resulting increase in bond length and the bandwidth reduction. The ground state magnetic properties are discussed in comparison to the metastable collinear antiferromagnetic state. Our work sheds new light on understanding the recent experimental results on the iridate heterostructures.