New Orleans Saints legend Willie Roaf is clearly disappointed with Alvin Kamara's arrest ... telling TMZ Sports the star running back just "can't do that, man."
The Hall of Famer said outside of a Super Bowl party at Academy in L.A. on Wednesday that even though the facts might not all be out surrounding the case at the moment, he's still pretty sure Kamara could've handled himself differently in Las Vegas last weekend.
"Whatever the situation was at the elevator -- you can't do that," Roaf said. "You can't do that, man."
"You just have to watch your environment. Probably some drinks involved, but, you know, you just can't do that."
As we reported, Kamara was arrested on Sunday after he allegedly beat up a man outside of an elevator at a Vegas hotel on Saturday.
In the police report, cops say Kamara was seen on video punching the man several times.
Roaf explained he doesn't necessarily think Kamara should be suspended over the alleged incident ... but he did add, "I know he needs to learn from this."
There's more -- Roaf also spoke with us about Michael Thomas' future in New Orleans, and he also said he doesn't believe newly retired Sean Payton is officially done coaching just yet.