You'd be foolish to avoid cardio, and not just because it burns calories. Elevating your heart rate is healthy. And in today's world you never know when you may need to run away from something.
If you overdo it on cardio you may lose some muscle mass but if you choose wisely it won't be a significant amount. Running long distance does tend to break down muscle but there's no need to run marathons; three miles at a good hard pace is plenty. Swimming is also good for burning calories without losing mass.
Just concentrate your cardio workouts on strength rather than endurance (e.g. sprints instead of distance) and you should be fine.