Mutation Testing has been proved to be effective in detecting faults. However, it suffers from the large number of mutants generated and analyzed when we apply the operators to create mutants. To alleviate this problem, this paper proposes an approach to find a reduced set of mutation operators that reduces the generated mutants and maintains the test effectiveness. Our approach adapts the semantic characterization of faults in order to find this set of mutation operators that will reduce the cost of Mutation Testing. The experimental results indicate that our approach is able to find a set of operators that reduce the mutation cost while maintaining the test effectiveness.