Time perception is not veridical, but, rather, it is susceptible to environmental context, like the intrinsic dynamics of moving stimuli. The direction of motion has been reported to affect time perception such that the movement of objects toward an observer is perceived as longer in duration than that of objects away from the observer. This looming-motion-induced time dilation has been explained in terms of an arousal-based or an attentional mechanism (or a combination of both). The current study was interested in which of these two explanations represents a more viable mechanism. With this aim, we investigated how the looming/receding temporal asymmetry is modulated by the emotional contents of stimuli. In two experiments, participants were shown face images expressing three emotions (angry, happy, and neutral) for one of seven target durations (400-1000ms) and performed a temporal bisection task by judging each presentation duration as “short” or “long”. In Experiment 1, the face images were shown in a constant-sized, stationary position. In Experiment 2, the images were expanding (looming) or contracting (receding) in size. In Experiment 1, we found no influence of facial emotion in perceived duration. In Experiment 2, however, looming stimuli were perceived as longer in duration than receding ones, replicating previous findings of the looming-induced time dilation using naturalistic human-face stimuli. More importantly, in Experiment 2 we found an interaction effect between arousal rating of faces and motion direction: The looming/receding asymmetry was pronounced when the arousal of the presented images was rated low, but this asymmetry diminished when arousal was high. These results suggest that (1) affective characteristics of looming stimuli can modulate temporal processing and more specifically, (2) the looming/receding asymmetry is reduced when arousing facial expressions enhance attentional engagement to receding stimuli, supporting the attentional mechanism of the looming-induced time dilation.