How can i lose belly fat without losing muscle mass?

I have been lifting at the gym for a year or so and has gained some muscle mass. However i have also gained a layer of fat around my lower abdominal. Now i know the only way to lose fat is by a combination of low calorie diet and cardio/aerobic exercises. But by doing these, it will also burn away my hard earned muscle. so i was wondering if any fitness/health experts can help me with this problem. Thanks