Actress Keira Knightley says she agreed to do romantic comedy "Begin Again", even though she finds the genre "tricky".

The 29-year-old tends to avoid lighter films, but couldn't resist starring alongside Adam Levine and Mark Ruffalo in "Begin Again", reports contactmusic.com.

She said: "After 'Anna Karenina', I realised that I'd done five years of work where I'd died or something horrific had happened to me in absolutely everything. I wanted something more positive and with hope in it.

"Romantic comedy isn't a genre I usually go to - it's one that I find quite tricky, but I thought this was strange enough with enough of a sort of acerbic quality to it," she added.