Fortunately, the three mechanics suffered only minor injuries but race stewards took a dim view of the incident in which the men were sent flying.
"It was a very dangerous manoeuvre which had potentially serious implications," they said in their ruling.
Kobayashi swiftly apologised for the accident.
"Of course I had to push hard for points, but without doubt I braked too late in the pit lane," Kobayashi said.
"The front wheels locked, I couldn't control the car, and this is how I overshot the pit box. I am terribly sorry this happened, and I hope the three mechanics I hit get well soon."
Two of the mechanics from the Swiss team needed treatment at the circuit's medical centre, one for an injured thumb and the other for cuts and bruises. The third suffered a bruised foot and was treated in the team's garage.
Sauber endured a miserable afternoon.
Kobayashi finished out of the points in 11th place, while Mexican team mate Sergio Perez had to retire after clashing with Williams driver Pastor Maldonado.
Maldonado was fined 10,000 euros for that incident.