MTV's "From G's to Gents" winner Creepa -- who was arrested last week for allegedly pulling off a counterfeit cash scheme -- insists he's INNOCENT ... telling TMZ, he was framed by a girl he thought he could trust.

As we reported, cops believe Creepa -- real name Thaddeus Chaylon Martin -- provided counterfeit U.S. bills to a female friend and had her buy a $145 cell phone at a SuperWalmart in Gainsville, FL.

Once the woman bought the phone, Creepa allegedly took it to a different Walmart and returned the phone for legit cash.

The woman told police she had no idea the money was bogus -- but Creepa tells us, that's a lie ... because she masterminded the operation, then pointed the finger at him when she got caught.

According to Creepa, the woman -- whom he met a few days prior to his arrest during a club appearance -- asked him for a lift to Walmart to buy a phone, with her own cash, and never once mentioned she was using funny money.

According to Creepa, he was totally unaware of her nefarious intentions ... and it wasn't until he was arrested that he realized what happened. 

Creepa adds, "That was my fault for giving someone a ride. You live and learn. It won’t happen again."