If pressure is applied to the equilibrium of solid $$\rightleftharpoons$$ liquid. The melting point of the solid may increase or decrease depending upon the nature of solid.
As, $$V\left(s\right) > V\left(l\right)$$ for ice-water and $$V\left(s\right) <V\left(l\right)$$ for others.
For most substances, increasing the pressure when a system is in equilibrium between liquid and solid phases will increase the phase transition temperature. Water is one of a few special substances for which the pressure lowers the temperature of transition. The basic reason is that water actually expands when it goes from the liquid to solid phase.