A cold-rolling method for modifying MFFK commercial microfiltration membranes based on the fluoroplastic F-42L has been developed and investigated. The method is based on the cold flow property of fluoropolymers and make it possible to alter the physical properties of a membrane without affecting its chemical structure. Scanning electron microscopy and capillary flow porometry studies have shown that this method also makes it possible to controllably narrow the through-pore diameter distribution, reduce the maximum pore size, and vary permeability depending on the applied force. In addition, rolling is a simple fluoroplastic-membrane modification process that is appropriate in engineering design and is easy to integrate into the membrane manufacturing cycle. According to available published data, this is a pioneering attempt to use the method for controllable reducing the pore diameter and narrowing the pore size distribution of fluoroplastic microfiltration membranes.