1:50 PM PT -- Rick might be doing okay, but Chris Evans says his "blood is boiling" over the random attack, and he wants the suspect located.
10:39 AM PT -- A rep for the actor tells TMZ ... Moranis was indeed assaulted on the Upper West Side. The rep adds he's fine and grateful for everyone's thoughts and well wishes.
Rick Moranis got a punch to the head during an unprovoked attack ... but the suspect was busted on video, and now cops are searching for him.
Law enforcement sources tell TMZ ... The "Ghostbusters" and "Honey, I Shrunk the Kids" star was walking on Central Park West Thursday in Manhattan when, out of nowhere, a man in an I Love NY hoodie unleashed a violent punch ... knocking Moranis down hard.
Check out the video ... Rick had zero time to react to the attack. Almost as frightening ... the attacker calmly continues walking away while Moranis lay on the ground writhing in pain.
Cops say Moranis filed a police report and went to a hospital for evaluation. He told docs he was suffering from pain in his head, back and right hip ... as first reported by WCBS.
Cops are now looking for the attacker. There's a $2,500 reward to anyone who provides info that leads to his arrest.