Riding Lawn Mowers

Brand new Husqvarna YTA24V48 riding lawn mower with an automatic transmission. I started it for the first time and the engine runs smoothly. However, when I start to depress the forward drive pedal(or reverse drive pedal), there is a "clicking" rattling noise that seems to be coming from a part on the chassis or in and around the belt drive. What is making this sound and is it harmful to any parts on the tractor? As a point of clarification, this sound/clicking/rattling is happening when the clutch lever IS NOT engaged.