what to do about a nypd sgt harrassing a non-profit and constantly moving them?

We are a tiny non-profit in NYC, New York City Homeless Advocates, and we began in 2012 and mainly work on 5th avenue and last year had no problem and most of this year. Then suddenly a NYPD sgt. started saying we can't set up to solicit donations for we are blocking sidewalk traffic, even though we weren't.

We let it go and moved to other spots.

Now he's really harassing us and says no 5th avenue whatsoever yet Salvation Army is EVERYWHERE. some 3 to a block and their set up is much bulkier then us, some use amps and sing and are loud.

We are legally incorporated, have an EIN, registered with AG office. We give items out to the homeless everyday and if you donate things to us we GIVE them to the homeless and DON'T sell them such as the Salvation Army does.

Anybody have laws I can site to get him to back off, other advice, links. should I threaten to sue the NYPD and take him to civil court since he's now stepping into violating civil rights and total harassment.

Appreciate any and all help.

Also, the stores have no problem with us, nor does the security (BID-business improvement district) for upper 5th). They know us, say hello, have see us help many homeless. It's this one guy, and he's not making it about the law as I see it, it's almost personal.