Video shows the moment the man sucker-punched the 67-year-old actor in the head.
It happened Thursday at 7:24 a.m. on West 70th street near Central Park West on the Manhattan borough's Upper West Side.
The attacker continued walking away after throwing the punch.
Moranis hurt his head, back and hip in the attack and went to the hospital for evaluation.
The attack sparked a strong reaction on social media from the Avenger's own Captain America.
My blood is boiling. Find this man. You don’t touch Rick Moranis. https://t.co/VXBbTjdDwa— Chris Evans (@ChrisEvans) October 2, 2020
Moranis may be best known for his work on "Ghostbusters," "Honey, I Shrunk the Kids" and "Little Shop of Horrors," among many others.