No-slip means the velocity is zero on the surface - it says nothing about the pressure field! On an aerofoil we'd have a no-slip condition but the pressure certainly varies around the aerofoil - otherwise lift could not be generated. Why do you expect there to be no variation in pressure? What configuration are you studying?

No-slip velocity means the magnitude of velocity doesn't vary with the length for those cells at the wall. It doesn't concern pressure. If you give more information about the problem, one could help you in setting up appropriate boundary condition for your simulation.