This paper proposes and investigates via numerical simulations the use of semi-active resettable devices for attenuation of cable vibrations in cable-stayed bridges. The resettable device studied in this paper consists of a piston moving inside a cylinder equipped with valves, and is essentially a pneumatic spring. The piston, connected to a vibrating cable, compresses the air when a valve is closed and thereby energy is stored in the device. By opening valves in a controlled manner this energy can be released into the atmosphere and cable vibrations suppressed. A model of a cable with a control device is proposed and numerical simulations are conducted. It is found that the use of this resettable device leads to improved suppression of cable vibrations compared to traditional viscous dampers.