"We don't feel his behavior was in violation of any protocol," Assistant Superintendent Ray Gadd said.
Meanwhile, two Mitchell High School students were arrested Monday for allegedly being involved in the Feb. 1 attack on 16-year-old Chase Cristia, who was seated at the rear of the bus, the Tampa Tribune reported.
A 17-year-old girl was charged with battery and a 16-year-old girl who authorities say recorded the assault with her cellphone and posted it on Facebook is charged with being a principal to battery. The girls' names have not been released.
Gadd said the bus was moving when the 17-year-old girl allegedly attacked Cristia.
The driver shouted at the attacker, Gadd said, adding that the incident began and ended quickly and the driver continued on his route.
"We are reluctant to pull buses over because that creates a safety situation as well," Gadd said.
Cristia was punched about 13 times and video of the incident was uploaded to the Internet, the newspaper said.
Tracy Cristia, the victim's mother, said Thursday she was baffled by the attack, the Tribune said.
"What if she would have gotten a hold of her face? I'm quite sure my daughter would have been in surgery that day," Tracy Cristia said. "God forbid, what if she had a weapon? What if she had a knife? It's not a far reach. These kids are doing crazy things."