The UN and the World Court both have warrants out for Netanyahu's arrest.
In fact, is would be illegal not to arrest him.
I hate to break it to you, but if Netanyahu or any of his staff came to NY or any other city in the United States, they fall under what is called "Diplomatic Immunity."
The United States is a signatory of the 1961 Vienna Convention on Diplomatic Relations. It shields foreign government officials from the jurisdiction of local courts and officials. This also includes "sovereign immunity," which protects sovereign states and themselves, their governments and their agencies.
Without these immunities, host nations could easily obstruct diplomatic dialogue by pressuring or harassing foreign representatives.
The US does have the option of sanctions, however, because this nation has been so divided within and our dollar has lost value and we've lost our triple A rating, our power to impose very effective sanctions has been somewhat diminished and could get worse.
So, he isn't going to be arrested. When these leaders from other nations come here, Significant armed security is absolutely required for them by the federal government and cannot be denied. So, if the fool thinks he can just send some local cops up to Netanyahu or any foreign leader and arrest them, they will just get their asses shot. Also, no cop would agree to it. Even they are familiar with Diplomatic Immunity. The mayor is just Grandstanding for the pro-terrorist mob.