It happpened at around midnight Friday when the Hempstead officer entered a McDonalds on Peninsula Blvd. and removed the man who was causing a disturbance.
Police say the officer re-entered the store and after exiting a second time the man hit him in the head with a piece of cement.
The defendant Oscar Guerra, 26, was arrested at the scene.
The officer was transported to a local hospital where he was admitted in stable condition.
Guerra is being charged with Assault 2nd Degree and Criminal Mischief 3rd Degree.