As people have been saying, a workout alone isn't enough to trim down or cut belly fat.
Best way to lose a bit of weight is to diet. But dieting doesn't just mean starving yourself with salads and an apple for the day - just reduce portions a bit, watch your calories, and maybe take a half hour walk/run every day. As long as you break a sweat, it'll be all you need.
Dieting is the key to weight loss, but it doesn't need to be extreme to see changes!