The court in Paris convicted the 32 on charges of obstructing freedom of expression over the incident in October 2011.
The group had stormed into the Theatre de la Ville, on the banks of the Seine near Notre Dame Cathedral, during a performance of "On the Concept of the Face, Regarding the Son of God", directed by Italian Romeo Castellucci.
The protesters had climbed on the stage, chanted and shouted, with some throwing smoke bombs. Three of the protesters were fined between €1,500 and €2,000, and the others between €600 and €800.
Prosecutors had requested fines of up to €5,000 each. Their lawyers said they would appeal.
"It's a lot to pay for shit!" said a lawyer for the defendants, François Souchon, saying that his clients also had a right to freedom of expression.
A lawyer for the city of Paris, which had lodged a joint complaint with the theatre against the protesters, said the court's ruling was a victory for freedom of speech.
"This decision recognises the supremacy of access to public culture and the absolute right to freedom of expression," Alexis Gublin said.
The play was the story of an incontinent man being looked after by his son.
A copy of a huge portrait of Christ by Renaissance artist Antonello da Messina hung at the back of the stage and appeared to be covered in excrement near the end of the performance.
Catholic groups said the imagery was deeply offensive and demanded the play be cancelled, though the association of French Roman Catholic bishops condemned the disruptive protest.