The singer/actress made her comments hours after a photographer was killed in an accident while he was following the singer's Ferrari in LA.
Bieber (18) was not in the car: it was being driven by a friend called Lil Twist.
Photographer Chris Guerra (29) was knocked down and killed by another vehicle while he was trying to take pictures of Bieber's car.
"Hope this paparazzi/JB accident brings on some changes in 2013," Miley (20) wrote.
"Paparazzi are dangerous! Wasn't Princess Di enough of a wake up call?!" the former Hannah Montana star said.
Police had pulled Bieber's car over for a check, and Guerra took pictures before heading back to his own car when he was struck by another vehicle.
"It is unfair for anyone to put this on to Justin's conscious [sic] as well!," said Miley.
"The chaos that comes with the paparazzi acting like fools makes it impossible for anyone to make safe choices."
Meanwhile Bieber has said his thoughts and prayers are with the Guerra's family.
"While I was not present nor directly involved with this tragic accident, my thoughts and prayers are with the family of the victim," he said.