The inward-pulling force of particles in the vascular space by proteins is called the

capillary oncotic pressure.

In the vascular system, there is the hydrostatic pressure that caused by the heart pumping the blood and oncotic pressure that caused mostly by protein. This pressure keeps the water inside the blood vessel and a change can cause some disease.
Low protein in the blood can cause edema which was the water inside blood vessel come out to interstitial tissue because the oncotic pressure is dropped.