Manziel, 22, is considered likely to start Sunday's game against the Bengals after another poor performance from veteran Brian Hoyer, who has been the No. 1 all season but has struggled as of late, ESPN's Chris Mortensen reported.
When Lewis was asked Monday about his thoughts on his team facing rookie Manziel, the coach said on WLW-AM in Cincinnati: "You've got to go defend the offense. You don't defend the player." After a short pause, he added, "Particularly a midget."
Hours later, Lewis reportedly issued an apology.
"I apologize to Johnny and the Browns and all the fans," Lewis said, according to Fox Sports Ohio. "It was just a poor remark. I really didn’t mean anything by it."
Manziel, the 2012 Heisman Trophy winner at Texas A&M, is listed by the Browns as 6 feet and 210 pounds. The team drafted him in the first round this year, with the 26th overall pick.
Manziel engineered an 80-yard touchdown drive in the fourth quarter of a 26-10 loss to Buffalo on Nov. 30. He ran 10 yards for the touchdown.