Every time I'm approached whilst flying I always think ,.. Well, it's one of two choices, either "they" want my autograph or I can't fly here anymore. When sharing this thought out loud as they approach, I generally am able to disarm the situation humorously.
At the monument grounds in Washington DC, I've had the park ranger cite the kite flying rules my club helped to write. We have the duty sergeant's desk (number programmed into our phones), if we need him <LOL> to reign-in one his overly enthusiastic amigos! It is best if someone else calls, so the ranger doesn't feel threatened and escalate the situation further.
Then there's the presidential helicopter overhead and snipers on roof-tops too, so we feel safe.