Check battery level, if greater than 40%, climb to 400 feet. Hide controller. Say I am not flying I was playing a video game on my phone. Let them leave, then you go to another spot and bring the mavic down even a couple blocks away.
This 40% is required in case they talk to you for long duration, and you will require a few minutes to get to your other location before you bring down the drone.
Try this at your own risk..
Generally though police have much better things to do, and they *have* to respond. Just play nice, even if you are in the right if you are fully legally allowed to fly where you are. If you treat them with dignity, you will get the same back.
This did not work when I crossed the border back into Canada from the US and they asked if I had fireworks, I said yes, They asked me why i had them, I said its Canada day, I was going to celebrate. They had to confiscate them and they wanted to "incinerate" them. I laughed, I said, OH so YOU get to light them and celebrate Canada day and I can't? With a bit of a smirk.. She did not like that.