A new method for the calculation of electric field distributions in the systems with spatiallyrestricted regions filled with polar media with nonlocal dielectric characteristics is proposed. The presence of regions with different dielectric properties in the system (as exemplified by the presence of an ion-filled cavity in which there is no polar medium surrounding the ion) is automatically taken into account within this procedure. The field distribution inside a uniform and isotropic nonlocal dielectric medium outside the spherical cavity containing a spherically symmetric charge distribution (the system represents the ion inside the polar solvent) has illustrated this new approach. In contrast to the previously suggested approach (dielectric approximation), where calculations of this characteristic required complex numerical and analytical calculations, the new method requires only single integration in order to determine the distribution of the potential of the electric field inside the polar medium with an arbitrary law of spatial dispersion of its dielectric permittivity (which can be specified eithter analytically or numerically).