Donald Trump -- Cuidado de Tu Mexican Employees ... Says Mana Singer Fher Olvera (VIDEO)

Fher Olvera, front man for Mexican rock band Maná ... thinks Donald Trump could have a revolución on his hands after his incendiary comments about Mexicans.

Olvera says Trump was "full of hate" during his Presidential announcement ... by saying most Mexican immigrants are drug dealers, robbers and rapists.

As he was leaving Toast in L.A. ... Olvera sheepishly told us Donald forgot one very important thing -- he's probably got lots of Mexicans on his payroll.

Uprising in the works? Check out Olvera's take.