Tyga -- I'm No Malibu Squatter ... I Got My OWN Mansion

Tyga INSISTS ... he's not some broke-ass squatter who's refusing to pay rent on a Malibu crib -- in fact, he claims he just bought a $6.5-million mansion 20 miles away.

TMZ broke the story ... a Malibu landlord named Gholamreza Rezai sued Tyga, claiming the rapper is screwing him on the $16,000-per-month rent ... but continues to live in the home.

But a rep for Tyga tells TMZ the lawsuit is 100% B.S ... insisting he gave the landlord the necessary 30 days notice before he left ... and everything should be square.

Tyga also claims he's definitely NOT living in the home ... because he's shacked up at a brand new 9,279-square-foot mansion he purchased in Calabasas.

The rep says the landlord is being unreasonable -- and wants to keep Tyga locked in the lease because he can't find anyone to cover the hefty rent in such a crappy economy.