An ultrasonic clamp coagulator assembly that is configured to permit selective cutting, coagulation and clamping of tissue during surgical procedures. An elongated portion of the instrument can be configured for endoscopic applications and has an outside diameter of less than 6 mm. The construction includes a clamping mechanism, including a clamp arm pivotally mounted at the distal portion of the instrument, which is specifically configured to create a desired level of tissue clamping forces. The clamping mechanism includes a two-piece pad design and pad material that enables the higher tissue clamping forces and a force-limiting mechanism that effectively smoothes out abusive tissue forces.