Soulja Boy -- I Never Told Cops Loaded Gun Was Mine

Soulja Boy never told police he owned the loaded gun found in his car ... and thinks cops violated his rights by searching him in the first place ... according to Soulja's manager.

TMZ broke the story ... rapper Arab was driving Soulja's car -- with Soulja in the passenger seat -- when they got pulled over for running a stop sign. LAPD officers found a loaded gun in the car ... and arrested Soulja on the spot.

But Soulja's manager, CEO Miami Mike claims a neighbor left the gun under the car seat and Soulja had no idea it was there. Further, he claims Soulja never admitted the weapon was his, and only told cops he owned the car.

Mike claims officers told Soulja someone had to take responsibility for the weapon -- but insists Soulja never copped to the gun ... just the vehicle.

We're told Soulja believes the whole search was illegal because cops didn't have probable cause.

But here's the thing ... according to law enforcement sources the gun was in plain view -- in which case officers wouldn't need a search warrant.