This paper reports a study on modulating the perceived stiffness by controlling the perceived force evoked from suction pressure stimuli. It demonstrates an early attempt of using suction pressure stimuli for augmenting the perceived stiffness of a spring. The purpose of this work is twofold; 1) to validate a requirement needed for the device in force enhancement applications, 2) to tentatively explore the effect of suction pressure stimuli on stiffness perception. In this study, we used physical springs for the stiffness stimuli, and a tool (tactile interface) was used for stiffness exploration. Human subjects were requested to explore and estimate the stiffness of a spring sample. Suction pressure stimuli were applied on the contact areas between the finger the tool during stiffness exploration. The amount of suction stimuli adjusts correspondingly with the measured force, but it is regulated by a psychophysical function. We introduced the gain to scale the measured force, thereby adjusting the profile of the pressure stimuli. We found that the perceived stiffness of the spring appears to increase with higher gain. The result seems to suggest that stiffness augmentation is feasible by modulating the stiffness perception using multipoint suction pressure stimuli.