Should i eat more or less calories?

I am 5'6 and weigh around 125. Don't get me wrong though, i have a lot of fat around my belly and a relitively weak body. I've started running almost everyday(i hear cardio is good for fat loss) and i've started lifting weights five times a weak, alternating arms and legs.(trying to gain some muscle) I eat really healthy, all of my carbohydrates are whole grain, I eat a lot of protein from shakes, eggs, khashi cereal, etc, and i get a ton of fiber from fruit. My question is should i eat more calories or less to lose the stubborn belly fat and gain muscle? I hear your body needs a calorie defecit to burn fat off the belly, but you won't gain muscle on your arms unless you eat more calories. I'm not fat, I don't want to lose weight, just gain muscle and get a flat belly. What should i do?