Vibration of an electric submersible pump assembly is monitored to produce a vibration spectrum. The vibration spectrum is compared to a known vibration signature for a pump condition that precedes gas lock. The pump condition is at least one of an impeller rotating stall condition, a diffuser stall condition, a pre-surge condition, and percentage of free gas within the wellbore fluid. Operation of the pump is then adjusted in response to the similarity of the vibration spectrum to the vibration signature for the pump condition to prevent impending gas lock.