The 25-year-old actress has so far appeared opposite established stars Priyanka Chopra and Kalki Koechlin.
Director Manish Tiwary told Hindustan Times: "Since the film is an adaptation of Romeo and Juliet, the chemistry between the two is very important.
"After a lot of search we have found the right girl. As of now, all I can say is I am very happy with Bachchi [her character's name in the film] and she certainly looks very good with Prateik."
A source said that the film's makers have put a veto on using cell phones on the set in case a picture is taken of the pair and leaked to the media.
In February, an unknown actress from Liverpool was cast opposite the actor in the remake of the Tamil hit Vinnaithaadi Varuvaayaa.
Prateik will next be seen in director Sanjay Leela Bhansali's My Friend Pinto.