The temperature dependence of the thickness of a nonfreezing water interlayer confined between an ice core and a smooth surface of quartz capillary is studied here theoretically, By using the principle of conservation of energy a first order differential equation is found. The equation relates the temperature and the film thickness via the film pressure (disjoining pressure). Molecular and structural components of this pressure are examined. Nonequilibrium and equilibrium solutions are compared with the respective experimental data. It is shown that disjoining pressure forces cause the lowering of the temperature in systems having confined phases.