How to solve the problem that guests smoke in non-smoking restaurants?

In the past, I would politely remind guests that this is a no-smoking area (usually marked). Please don't smoke here. Generally, guests with a little quality will definitely say sorry. If they don't pay attention, they will put out their cigarettes. If they encounter poor quality or drink too much, don't talk nonsense with him. It's no use. I can only ask PA to clean up later. I hope my answer is helpful to you. I hope it can be adopted. Thank you~