Thank you so much pierremgi!
Edit: This is odd, I tried some variations of the code you provided, however it does not seem to stop the spawn of a vehicle.
I tried {MGI_BLACKLISTVEHRESPAWN pushBackUnique _x} forEach [a1,a2]
{MGI_BLACKLISTVEHRESPAWN pushBackUnique [a1]};
{MGI_BLACKLISTVEHRESPAWN pushBackUnique _x} forEach (vehicles select {_x inArea thisTrigger});
None of them worked even when the trigger was activated(I set a hint to know if it reached the end of the activation code), could this be related to the use of other mods like ACE, CBA ....?