Lindsay Lohan stiffs photog

Lindsay Lohan hasn't paid her settlement in a lawsuit with a photog and he wants his money.

Photographer Scott Nathan sued Lindsay's clothing line, 6126, claiming he was never paid for his work.

The lawsuit settled for an undisclosed amount back in December -- and according to docs filed last week, 6126 was supposed to making payments beginning in March ... but so far -- nothing.   Now Nathan is asking a judge for an order to enforce the settlement -- attaching bank accounts, etc.

A rep for Lindsay told TMZ, "We don't comment on any pending legal situations with third parties."

LAMediaWatch.com