Interface states have great practical applications, therefore, searching for the existence of interface states has both scientific significance and application prospects. In this work, we construct a two-dimensional phononic crystal with an oblique lattice possessing linear Dirac dispersion, by tilting that phononic crystal with a square lattice. Dirac dispersion causes a π jump of the Zak phases of the bulk bands, so that the projected band gaps at both sides of the Dirac cone have opposite signs of surface impedance, resulting in deterministic interface states at the interface formed by the phononic crystal with a square lattice and its tilted partner.