The "beach police" (pith helmets and white uniforms) are a private security firm hired by the government to patrol the beach. They are not actual Police Officers in the traditional sense. That is why they are limited in their enforcement capacity. They are there to assist you, so by all means approach one should you have a need or an issue. As mentioned, they can detain (and apprehend) but cannot arrest. They call in the police to do that.
They are there to help you, not to interfere in what they may perceive as a normal tourist activity, which can encompass some very "strange/odd - wide range" of behaviour at times... (grin)