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.

As for Tyga’s new crib (above) — we’re told it’s ginormous … boasting 7 bedrooms, 8 baths, a movie theater, pool spa, waterfall, tennis courts, gym — the works.