Why did the French discourage Washington from attacking New York during the revolution?

During the Revolutionary War, the French and others discouraged George Washington from attacking New York. However, there were New York and New Jersey campaigns to strike against the British who had total control of the harbor in New York during the entire war until the end.

The French discouraged George Washington from striking against New York because it would cause most of his troops to have to travel so far north to attack that it would cause his troops to become too thin and not enough of them.

Therefore, Washington focused on striking a bunch of little sites that were close together. Then the troops in Washington’s Continental Army could take over each site before moving to the isolated places of the colonies.