Fine, that's fair. But even the police can be wrong in their actions. In fact, the reason all of this is happening now is because a police officer killed a man, and none of his colleagues stopped him.
We can't assume they always act in good faith. Where in the constitution does it say the police has the power to override people's rights to assembly if the President wants access to the location in which they are assembling? Law enforcement has to enforce the law, but here there was no law to enforce.