Kourtney Kardashian -- Male Model Says DNA Test Is BS

Kourtney Kardashian's DNA test doesn't prove jack ... so says the male model who insists he's the REAL father of her 3-year-old son Mason, not Scott Disick.

Michael Girgenti tells TMZ, he saw the DNA test results TMZ posted on Thursday, which Kourtney got from an independent lab, showing that Scott is Mason's dad -- but Girgenti insists those results could easily have been forged.

As a result, Girgenti is refusing to back off his paternity lawsuit, in which he claims he knocked up Kourtney in 2009 after meeting her at a photo shoot ... and Mason is the result.

Girgenti tells us he won't be satisfied until a court-monitored DNA test is conducted.