Rich Homie Quan -- Sorry, I Smoked with My Baby ... I'll Try to Do Better

Rich Homie Quan is copping to making a huge mistake when he lit up with his infant on his lap -- question is ... will it be enough to spare him a Child Protective Services investigation?

Quan says, "I would like to apologize to my son,(Royal) my fans and all the parents around the world.By no means would I do anything to hurt my son or any kid in the world.I regret that I chose to continue to smoke once Royal jumped in my lap."

He put up a pretty loving pic of himself with Royal, and added, "I am sorry for my actions." He never says exactly what he was smoking -- marijuana or a hand-rolled cigarette.

TMZ broke the story ... CPS and police in Georgia launched an investigation after seeing the smoking video, which RHQ posted himself -- and after getting flooded with complaints.

RHQ says in spite of this mistake he'll "continue to strive to be the best parent I can be."