Oscar De La Hoya -- I'm Never Coming Back ... Not Even For Mayweather

Oscar De La Hoya has made up his mind ... the 42-year-old boxer says he's NOT going to unretire and get back in the ring ... even if Floyd Mayweather wants to fight.

As we previously reported, Oscar has been saying he thinks about making a comeback EVERY DAY of his life ... and told TMZ Sports he has his eyes set on human wrecking machine Gennady Golovkin.

But Wednesday night, seems common sense finally set in ... and De La Hoya said he's 100% DONE -- even if Mayweather offers big money for an extra-belated rematch from their 2007 fight.

By the way, Mayweather "retired" from boxing after that fight ... but ended up coming back.