Madonna has issued an apology after she referred to her 13-year-old son, Rocco, as the N-word in a photo she posted on Instagram earlier this month.

"I am sorry if I offended anyone with my use of the N word on Instagram," Madonna wrote on the photo-sharing app yesterday, Jan. 18. (The post has since been deleted.) "It was not meant as a racial slur…I am not a racist."

"There's no way to defend the use of the word. It was all about intention," she continued. "It was used as a term of endearment toward my son who is white. I appreciate that it's a provocative word and I apologize if it gave people the wrong impression. Forgive me."

The picture in question (which has since been re-captioned) showed Rocco in a boxing stance, and the 55-year-old pop icon had captioned it, "No one messes with Dirty Soap! Mama said knock you out! #disn---a"

In addition to Rocco, Madonna has three other children: 17-year-old Lourdes, and David and Mercy, both 8. David and Mercy, who are both black, were adopted from Africa.

This is the second time this month that Madonna ignited an Instagram controversy regarding her son Rocco. Just a few weeks ago, the singer posted a picture of the 13-year-old holding a liquor bottle. Madonna had captioned the photo, "The party has just begun! Bring it! 2014"