(If this sounds familiar, it's because about two years ago, the same thing happened in in Washington DC.)
NYPD Sends Out Official Memo Telling Officers They’re Allowed to Be Photographed, article.
Here is part of what the police (!) wrote to their officers:
Members of the public are legally allowed to record police interactions. Intentional interference such as blocking or obstructing cameras or ordering the person to cease constitutes censorship and also violates the First Amendment.