Controlling the gripping force on objects has been a challenging task for industrial grippers. Its realization often requires an electric gripper with embedded force sensors and control feedback. This approach is costly and introduces extra complexity for grippers. To avoid damage while handling fragile objects, this paper presents a novel force regulation mechanism (FRM) to be installed on grippers. Without using additional sensors and control, the FRM can passively produce an adjustable contact force between the finger jaws and objects of variable sizes. Together with pneumatic grippers which are much less expensive, this approach offers a more attractive solution in terms of cost and complexity. In this paper, the design concept and simulation results are presented and discussed. A prototype of a gripper with the proposed FRM is illustrated to demonstrate the effectiveness and accuracy of force regulation. This novel mechanism is expected to serve as a reliable alternative for industrial object manipulation.