This paper presents the performance analysis of a haptic feedback teleoperation system for robotic-assisted surgery. Through a haptic device, the surgeon tele-operates the medical instrument, fixed on a remote robot that may evolve in free space or in contact. In free space, the surgeon feels the motion of the robot. When contact with tissues occurs, an on-line environment stiffness estimation is performed using an Extended Kalman Filter with robot modeling error compensation and without considering the contact position. The quality of the telepresence will depend on this estimation. Based on the stability and transparency frequency analysis, the estimated parameter is used to tune the teleoperation scheme and to improve telepresence. The improvement is based on the stability of the haptic feedback teleoperation scheme new rearrangement in which we distinguish between voluntary and involuntary operator positions.