Cameron Diaz came to the rescue of a stranger who accidentally set his menu on fire on Sunday evening at West Village favorite Rosemary’s. A fellow diner tells us Diaz — who’s in town filming the Fox movie “The Other Woman” with Leslie Mann — was dining at the Italian trattoria with a group of women, when she noticed a diner at another table accidentally set his menu ablaze with a candle. Our witness said, “Cameron spotted a menu at a stranger’s table catch fire, then ran over to blow it out. She was really sweet.” In the movie, Diaz’s character meets her dream man, only to discover he’s married. Nicki Minaj and Kate Upton also star in the comedy.