Coordination of base stations is essential in the mitigation of inter-cell interference in cellular communication systems. One of practical solutions is a cluster-based inter-cell scheduling where base stations in each cluster determine their transmissions in cooperative fashion. In spite of potential performance improvement, the inter-cell scheduling may result in conflict between clusters. However, a dynamic coordination in the cluster level is difficult due to the prohibitive burden of inter-cluster communication. In this paper, we address the coordination of clusters in the downlink of cellular networks. We propose a rule of inter-cluster coordination, namely nominal scheduling order with penalty (NSOP) which does not require communication between the clusters. Dynamic system level simulations are performed to examine the performance of the NSOP in various interference scenarios. It is observed that the proposed NSOP effectively strikes a balance between the inter-cluster interference avoidance and the intra-cluster multi-user diversity by means of a simple penalty factor.