He tells British morning show Daybreak, "I always thought it was going to be this soft sensual sort of moment, and suddenly there was this vigorous kissing happening to me.
"She is a bit of an animal... But then, I'm not complaining. There are tens of thousands of men that would cut off limbs to be in that position."
And the shoot wasn't as romantic as it appears in the movie - co-star Rupert Grint was so tickled by the scene, he was forced to take a break to recover from his giggles.
Daniel Radcliffe adds, "Rupert actually had to leave (the) set, because he was laughing that much."