Justin Bieber Mobbed AGAIN!

Justin Bieber and Sean Kingston were driving along Miami Beach minding there on business until they got noticed and had a huge crowd swarmed the car. They then had to flag down a cop to protect them from adoring fans.

Apparently, Justin was driving Kingston's Rolls-Royce  -- with Kingston riding shotgun -- when a group of fans noticed them and started to gather around the car.

We're told Justin and Sean got the attention of an officer who had to contain the crowd until they were able to get far enough away! Poor Justin! He can never do anything without being ambushed! I guess that's all part of the game!