The 39-year-old actress is currently single after dating a string of hunky Americans like Justin Timberlake, Jared Leto and Alex Rodriguez.
She said that she is impressed by British manners, and sees Firth as the epitome of an English gent, reported Contactmusic.
"I love (British men's) sense of humour and the sense of chivalry and charm. It's something that is innately a part of the culture - it's not the same in America."
"He's (Firth) the perfect Englishman. Just enough of the self-effacing to a point that it's comfortable for other people, but also totally charming and engaging to where he makes you feel special. He's got that British honesty," Diaz said.
"I love the Brits - I always have. I have a weak spot for them. I grew up on Monty Python. I love Little Britain. My grandfather used to watch Benny Hill all the time," she added.