The Weeknd Cuts Selena Gomez's PDA Short in Argentina

The Weeknd was all about Selena Gomez's public cuddling ... until he noticed paparazzi watching.

Paps got the couple Tuesday showing some extreme PDA while strolling around Buenos Aires before Abel's gig later this week.

He seems down with her clinging onto him ... but watch what happens when he sees the camera guy across the street.