A model is suggested that describes the observed dependences of the strength of laminated metal/graphene composites on the lateral size of graphene platelets. Within the model, these dependences are associated with the accumulation of dislocations at metal/graphene interfaces and dislocation pinning by the edges of graphene platelets. It is shown that the strength of laminated metal/graphene composites depends not only on graphene platelet dimensions and the orientation of the applied load but also on the specific energies of metal/graphene interfaces and lamella boundaries. This can enable one to control the strength of laminated metal/graphene composites by tuning their interface properties.