There's a new movie being shopped around about Richard Williams -- Serena and Venus' father -- and it appears Will Smith is the #1 choice to play the #1 dad.

But, there's been a major backlash from people who say Will's complexion is too LIGHT to match the real Richard ... and critics are already calling for potential producers to find a more dark-skinned actor.

Steve Harvey doesn't see it that way ... telling TMZ Sports the beloved entertainer can do no wrong.

"Hell yeah, Will Smith is a good choice for everything."

Smith hasn't officially signed on to the project or even commented about it publicly. The project is only in the "spec script" stage.

However, there's been a push on social media for other actors to get the lead role -- suggested names have included Don Cheadle, Forest Whitaker and even Usher.

We asked what Harvey thought about the latter ... and it's safe to say he ain't buyin' it.

"Come on, man."

As for the biopic ... Deadline reports its working title is "King Richard" and will tell the story of how the world's most famous tennis parent raised the 2 sisters from the streets of Compton to international tennis superstardom, despite Richard having no real tennis experience of his own.