The fundamental and technological interest for thin La0.67Sr0.33MnO3 (LSMO) films is basically determined by the attractive possibility to stabilize bulk-like properties (magnetism and metallicity) at interfaces making thus accessible the advantages of half-metallic manganites for tunneling magnetoresistance (TMR). A new approach that we used for engineering of interfaces of LSMO ultrathin films is an insertion of additional SrO monolayers, which form the so-called Ruddlesden-Popper (RP) structures at interfaces [1]. For this study we applied both SQUID magnetomety (the measurement covers a temperature range 2-400K) and magneto-optical Kerr effect (MOKE), which are two complementary techniques for defining magnetic properties of thin ferromagnetic films, as MOKE allowing to investigate angle-resolved hysteresis loops and understanding magnetic domain structure. In this study LSMO films were prepared and interface engineered by metalorganic aerosol deposition technique on SrTiO3(100) substrates (STO). SQUID revealed retention of a high Curie temperature 337K for the thinnest 5 nm LSMO interfaced film. The saturation magnetization, normalized on the number of Mn ions, consists of 3.6 μB/Mn and exceeds significantly the corresponding values obtained for the optimally doped manganite films with the same thicknesses. All films independently of thickness and interface modification present uniaxial magnetic anisotropy. The directions of the easy axes for unmodified films was [100] with respect to the crystallographic directions of the cubic STO with an orthogonal arrangement of the hard axis. The creation of RP interface between substrate and LSMO layer rotates the uniaxial system in-plane to [110] direction. The Stoner-Wohlfarth model was used to validate results obtained for hysteresis shapes, coercivity, and saturation fields. Unusual uniaxial anisotropy of thin LSMO films on a nominally flat STO(001) substrate [2] is under discussion. These results are promising for the future realization of room-temperature TMR devices making use of the RP-like engineering of interfaces.