People seem to forget that the police eventually cleared the Occupy Wall Street people out of their park and several hundred were arrested in the process. And since the Occupy Wall Street mob didn't take over any federal property then there wasn't a reason for the feds to get involved.
They just blocked traffic and commerce for a long tine. And I remember the police allowed the protesters to continue even after the riots and destruction of private property.
To be fair they should have arrested every one of them.