In social interactions, interpersonal distance influences relationships, provides protection, and regulates arousal. Despite the intuitive nature of adopting specific distances, little is known about comfortable interpersonal distances with social robots. Here, 66 participants saw individuals standing face-to-face with a robot at different distances and pressed a button when seeing a woman or a man (in different blocks). In line with the negativity bias hypothesis, suggesting quicker reaction times to negative stimuli, participants showed a preference for increased distances, resulting in longer reaction times. Human-likeness of robots moderated the link between distance and arousal. The most human-like robot was less liked and evoked higher arousal. These findings have implications for designing social robots and optimizing interactions, particularly in educational or medical contexts.