Heat oil in large skillet over medium-high heat until hot. Add chicken, onion and bell pepper; cook and stir until chicken is browned.
Stir in water, tomatoes and tomato sauce. Bring to a boil. Add ravioli; carefully stir until separated and covered with tomato mixture. Cook 12 to 15 minutes or until sauce is of desired consistency and chicken is no longer pink, stirring frequently to prevent sticking.