The 29-year-old was with the remainder of the film's cast when someone from the gang threw a stone Monday.
She took to Twitter to share her angst, and wrote: "A stone was thrown at me on stage in Faridabad, it hit and hurt my lip, for the primary time in my life, I'm truly ashamed of our people."
"It's deeply disheartening to must say horrible things about my country... but this was uncouth and had it was someone 'more important' it might not have gone down well," she added.
According to an eyewitness, "Sarah was in tears the instant she was hit and it led to slight swelling. However, ice was immediately applied at the injury."
The event was titled an "adult party" and Riteish Deshmukh, Tusshar Kapoor and Neha Sharma were also on stage.
Following the incident, Sarah and Neha didn't stage their performance and were sent to their van.
"The man who threw the stone couldn't be identified," the source added.
Sarah says though she is not satisfied concerning the incident, it has didn't dampen her spirits in any way.
"I'm not okay but when they were seeking to defeat my spirit, it hasn't worked," Sarah wrote.
"Kyaa Super Kool Hain Hum", produced by Ekta Kapoor, is a sex comedy, releasing Aug 3.
