Recent studies have demonstrated that numerical magnitude and specific finger movements processing interfere with each other. On the basis of these interactions, the present study investigated whether action observation was able to influence a random number generation task. This task required participants to randomly produce numbers between 1 and 10 after they observed action stimuli. Those stimuli were either closing or opening movements of fingers, hands or mouth, or a stimuli color change (a control comparison condition). The results revealed that random number production was influenced by the prior presentation of the finger grip movements, whereby observing a closing finger grip movement led participants to produce more small than large numbers, while observing an opening finger grip movement led participants to produce more large than small numbers. For the hand movement conditions, the influence on number production was less striking while the influence of the mouth movements was restricted to the opening movement with an overproduction of large numbers after this condition. Finally, stimuli color change conditions did not influence the number production task. Taken together, these results showed that some of the characteristics of the observed finger, hand and mouth grip movements appeared to automatically prime the number generation task. The findings are discussed in terms of the functional and neural mechanisms that might explain the effect, and support the view that number semantics might be grounded on sensory-motor mechanisms.