Director Madhur Bhandarkar finds it "disgusting and highly condemnable".
"Shocked to hear that Gauahar Khan got slapped for alleged indecency. Absurdity just touched a new level. Disgusting and highly condemnable," tweeted the "Chandni Bar" director.
Gauahar was slapped Sunday night on the sets of singing reality show "India's Raw Star" here. The accused was one of the audience members.
Farhan took to Twitter to express his anger.
"Dearest natural selection, please help us out-evolve morons like the one who slapped Gauahar Khan. Sincerely," he tweeted Monday.
Actor Rohit Roy was left "speechless" after reading the headline: "Man slaps actor Gauahar Khan for 'wearing indecent clothes'."
Sharing a shot of the story, he captioned it: "Headlines of today! I mean, seriously?? Have I moved to Taliban country ?! #speechless".
The case is being investigated.
An official from Aarey Colony police station told IANS: "Last night (Sunday night), the accused Mohammad Akil Malik was brought here and he is in our custody. We are investigating this case."
The "Rocket Singh: Salesman of the Year" actress had sought help from police Sunday night itself.
Zonal DCP Panjabrao Ugle added: "Gauahar Khan was shooting last night so, after finishing her shoot she came to the police station and we have already recorded her statement. Now, the case has been registered and we are taking care of it".
The accused had been reportedly observing the model for the last three days. On Sunday night, he suddenly got up and went to the stage.
He initially tried to touch her and then slapped her. He is likely to be booked on charges of molestation and assault.
He asked her how could she wear skimpy outfits and dance to cheap songs despite being a Muslim.