This paper addresses the problem of channel allocation in Cognitive Radio (CR) networks. CR has been considered as a technology which improves spectrum utilization significantly by carrying out Dynamic Spectrum Management (DSM). One issue of the DSM is the using of frequency channels by secondary/CR users that are under-utilized and/or not used by primary users. CR users eager to use them when they are not used by primary users. The number of these spectrum bands is limited. This scarcity leads to conflict among CR users; As many as bands used by any CR user leads to decaying objective functions of other users. Thus, they have a destructive effect on each other. The paper models this conflict as a new multi-objective problem. Pareto set is attained via a Multi-Objective Optimization (MOO) technique, namely ε - constraint method. Results show the efficiency of the method.