Boxing superstar Andre Berto says he spoke with Conor McGregor earlier this week -- and tells TMZ Sports he strongly feels the guy should NOT rush into a rematch with Nate Diaz.
Berto's not just a premiere boxer (fighting Victor Ortiz in April) -- but he comes from an MMA family with his father, brother and SISTER all having competed in the Octagon.
So, when Berto told us he's been in contact with The Notorious ... we had to ask if he had advice for the UFC star.