Francis Ford Coppola -- There Should Have Only Been ONE Godfather Movie

"Godfather" director Francis Ford Coppola says "Part II" -- which many consider the greatest sequel of all time -- was a MISTAKE ... insisting, "There shoulda only been one."

Coppola was leaving Hemingway's Lounge in L.A. last night when we asked if he would ever pick up the Corleone storyline for another GF flick when he dropped the bombshell.

We agree about GF3 -- but TWO? Two was AWESOME -- with Al Pacino, De Niro ... the trip back to Italy -- C'MON!!!!

So, we gotta ask ...