Easy, there!
easy there
Slow down; relax. Whoa, easy there, buddy—I don't think they'll be more inclined to help you if you go into the store yelling like a lunatic. "Easy there, boy!" I said as I pulled on my dog's leash to slow him down.
Easy, there!
Calm down! "Easy, there!" said Arizona Slim, patting his horse's neck. Easy, there! Before you start yellin', tell me what you're yellin' about.