The 'Under The Bridge' drummer admitted that his facial likeness to the comedian causes him problems with members of the public.
"People who come up to me are drummers or fans of the band. I don't get it too much, but I'll be somewhere and someone will have me take a picture or something," he told Rolling Stone magazine.
"Someone else will see that and they'll come over and and say 'Will Ferrell?' I have to say 'no', and they'll be like, 'Bulls**t, man. I just saw you taking pictures with that man? Why do you have to be like that?' I'm just like, 'Dude, I'm telling you, I'm not Will Ferrell'."
Smith added: "So, a lot of the time it's easier to just agree with them and take the picture and they go away.
"It's weird to look like someone so much that people aren't even asking if you're the guy. They just come up saying, 'I loved you in that movie'."
Watch the video for Red Hot Chili Peppers's 2003 single 'Can't Stop' below: