You likely will not gain any muscle while on a deficit. You'll actually be lucky if you don't lose any muscle. Cardio will only increase the deficit you are creating. Cardio will generally increase your rate of muscle loss (especially steady state low intensity cardio).

Cardio is, however, generally a healthy thing to do and is great for the body in other ways such a promoting blood flow and strengthening the cardio-vascular system (never a bad thing).

I think if you're interested in maintaining your muscle mass then a healthy balance of cardio and diet-induced deficit is probably in order.

IW