This paper presents a model of nonverbal communication and interpersonal relationship between virtual actors. Nonverbal communication improves their believability. They react not only to the presence of the other actors but also to their postures. Furthermore, their interpersonal relationships are affected by the issue of social interactions. To avoid homogenous group behaviors, each actor is set with a different character profile. We present an application of this model to create actors involved in social interactions in a virtual public garden. The animation of virtual actors is based on the library AGENTlib which is dedicated to the management of agent entities able to coordinate perception and action.