The 48-year-old recently revealed he sent Armie an email after replacing him alongside Jennifer Lopez in Shotgun Wedding.
The casting swap came in February after Hammer stepped down amid allegations he had sent women Instagram messages describing violent sexual acts, including rape and cannibalism.
Speaking out to fashion magazine Man About Town, Duhamel revealed he reached out to Armie via email to clear the air after taking his role.
"I know Armie a little bit,” he said.
"And when I knew I was gonna get the part I emailed him and said, ‘Listen, I know you are going through it right now, I don’t like to get roles like this and I just wanted to let you know that I am thinking about you and good luck, get through it,'" he explained, before revealing Hammer emailed him back.
“[Hammer] emailed me right back and said thank you,” he continued. “So who knows, hopefully he gets through it.”
Fans immediately slammed Duhamel, calling him out for seemingly supporting the actor amid Armie's sexual scandal.
But Duhamel didn't take the criticism lying down.
In an exclusive DM conversation with an angered fan -- which was captured by Deuxmoi -- he explained his reasoning in detail.
"I don't support any of his behavior, but I choose to believe people can learn from their mistakes and grow," Duhamel responded to someone who sent him the article with a garbage can emoji.
"I don't believe in cancelling or casting people aside because I don't believe in what they do," he continued, "I pray the guy gets the help he needs."
The fan then responded, "I understand what you're saying, but he is being accused of rape and physical abuse towards multiple women. I would hope you 'don't believe' in what he does because it's horrible and disgusting. I feel for his victims, not him."
Josh immediately wrote back, "I just said I don't support any of his behavior."