The What's Your Number? actress stars alongside Cohen in upcoming comedy The Dictator.
Faris confirmed that shooting on the film had been completed over the summer and that it is due to be released next spring.
"He's amazing," Faris said to Digital Spy of working with Cohen.
"He's a genius, this comedic genius, you have to be on your toes. It's challenging, but it was really, really fun. Just crazy though."
Other actors confirmed for Cohen's film, which is directed by Larry Charles, include Ben Kingsley and Megan Fox.
Watch Anna Faris talk to us about The Dictator below: