Lil Wayne & Birdman: Friendly But Biz is Biz ... Lawsuit Still On!!

Lil Wayne and Birdman's warm fuzzy reunion in Miami does NOT mean their beef is squashed ... TMZ has learned Wayne's pushing forward with his lawsuit.

When the Cash Money honcho stood shoulder to shoulder with Weezy Sunday night and declared he'd die and kill for him ... it looked like they'd finally patched things up. Not so.

According to our Young Money sources, Wayne isn't softening on his main demands -- release "Tha Carter V" and cough up the millions he says Birdman owes him. The stakes are high ... remember Weezy's threat to take Drake and Nicki Minaj with him if he leaves Cash Money.

As for the Miami love-in? We're told that was mostly sentimental, and Birdman's attempt to repair the personal relationship before fixing biz ties.

We're told there's still NO settlement talks, but late Wednesday there was one strong sign the cold war could be ending -- Wayne and Birdman in the studio together.