Angle tells TMZ .. his mother recently received a call from someone in the Domincan Republic who claimed her grandson was in a local jail and needed $4,000 STAT ... or the consequences would be severe.

Angle's mom, who lives in Pittsburgh, wired the cash and thought everything would be fine ... until she got another call the next day ... demanding an additional $4,000.

Mama Angle couldn't afford the payment ... so she contacted Kurt ... who had a feeling the whole thing was a scam and reached out to the family member who was supposedly in danger.

Turns out, the family member was FINE and hadn't been to the D.R. in over a year ... so Kurt contacted local authorities to get to the bottom of the situation.

According to the FBI, Kurt's mom is just one of MANY victims being targeted by international scammers who prey on the elderly.

Kurt tells us he has a feeling the people who duped his mom have an accomplice working near her home in Pittsburgh ... because they knew about his family ... and managed to find his mother's unlisted phone number.

"I'm gonna find the [explicative] who did this to my mom," Angle tells us ... adding, "I don't want this happening to anyone else!"