Madonna says she had no idea people would take such offense over her use of the n-word yesterday -- even though at 55 she probably should.

Madge released a statement moments ago saying she's not a racist ... and her use of the hashtag "#disni**a" in reference to her son on Instagram Friday was not meant as a racial slur.

Madonna explains, "There's no way to defend the use of the word. It was all about intention ... It was used as a term of endearment toward my son who is white."

Madonna adds, "I appreciate that it's a provocative word and I apologize if it gave people the wrong impression. Forgive me."

Translation: I should stay off Instagram.