Three teachers and a university guest were forced to pay almost £400 after their cars were clamped by the head teacher from a neighbouring school.
Avtar Mangat, from Wilkes Green Junior School, Birmingham, ordered the cars being used by people at Wilkes Green Infant School to be immobilised.
He said his staff were unhappy with their cars being blocked in on the site they share with their colleagues.
The National Union of Teachers condemned the action as "childish".
Three teachers who are represented by the NUT complained to the union following Wednesday's action.
Mr Mangat said clamping notices had been put up four months ago and that he had called in a private firm to clamp the vehicles on the wishes of his school's governing body.
The Local Education Authority was called to the schools in Antrobus Road, Handsworth, but came without the correct paperwork to free the cars.
It will now have to pay the bill.
Gerard Paisley, head teacher of the infants school, said the action had been a waste of public money.
He admitted his employees' cars had not been parked in their designated spaces but said he did not expect his female staff to park in the road and walk to the site when they worked late.
Birmingham City Council said it advised the junior school against clamping and had been trying to get the schools together to discuss the situation.
It said it would continue to work with both of them to resolve the problem.