Not Interested In Jake Paul Fight

Jake Paul vs. Manny Pacquiao is a fight you will NOT see ... 'cause the Filipino legend tells us he's laser-focused on bolstering his legacy -- and a fight with the YouTube star doesn't help.

... but he didn't slam the door on Manny Pacquiao vs. Floyd Mayweather II.

TMZ Sports talked to the 42-year-old boxing great while he was training at Wild Card Boxing in Los Angeles ... and we asked Manny if he had any interest in boxing Jake.

"No, I will not. I will not. I want to fight the best to add on to my legacy."

Of course, 24-year-old Paul -- who's fighting ex-UFC champ Tyron Woodley later this month -- previously told us he had his sights set on ... the top pound-for-pound fighter in the world,…