Stop the person, have a conversation, ask him what he said

and meant. See how it goes and decide whether to call a police. This is hypothetical. Below is real:

2021, afternoon, I was taking a pic of a public high school bdlg. a white male said to me from his truck, "hey, you may want to speak to someone and make sure you have proper authorization." I said, "what authorization? I am taking a pic of a public bdlg." he was adament, "you want to make sure." "thank you for the reminder, i think it is within my right to take a picture of a public bdlg," i did not stop there, "were this not allowed, what had this country become, a banana republic? if you see this as a problem, feel free to report to the authorities." that shut him up. of course, it was safe for me to confront him right there.

there were other occasions in which i had no chance to fight back, i admit. i fight back whenever i can.