Yes, Priyanka refused to kiss Harman in the film though the latter was keen on locking lips. Priyanka revealed that she wouldn't do certain things on screen irrespective of the co-star. Harman also admitted that Priyanka objected to the kissing scene in Love Story 2050 though he and his dad wanted one. He added that he respected her decision.
But the big question is why Priyanka refused to kiss Harman when she had earlier kissed her co-star in the film Andaaz. May be the actress is not sure of Harman!