Plastic pollution has been identified as a major threat for coastal marine life and ecosystems. Here, we test if the feeding behaviour and growth rate of the two most common cold-water coral species, Lophelia pertusa and Madrepora oculata, are affected by micro- or macroplastic exposures. Low-density polyethylene microplastics impair prey capture and growth rates of L. pertusa after five months of exposure. Macroplastic films, mimicking plastic bags trapped on deep-sea reefs, had however a limited impact on L. pertusa growth. This was due to an avoidance behaviour illustrated by the formation of skeletal 'caps' that changed the polyp orientation and allowed its access to food supply. On the contrary, M. oculata growth and feeding were not affected by plastic exposure. Such a species-specific response has the potential to induce a severe change in coral community composition and the associated biodiversity in deep-sea environments.