I believe the answer is no as long as you are not interfering with the police officer's official business. Police demand all sorts of things though that they aren't exactly entitled to, so don't be surprised if you are told to turn it off.
I once had a police officer tell me that I couldn't be standing on the sidewalk while one of his fellow officers was writing a ticket for a bicyclist (this was during Critical Mass). I stood around for a while longer until he was in my face yelling an order to disperse at me. I've since learned that such an order is not valid unless I'm somehow breaking the law. But since I didn't know that at the time, I left. Next time I'll stand there and likely get a ticket or arrested for some baloney charge.