“While attempting to provide unnecessary social commentary about the current selfie culture, I (in true a–hat form — thank you Jeffrey Dean Morgan) inadvertently offended many who were genuinely grieving the loss of a true icon,” Hammer wrote.
“I want to apologize from the bottom of my heart and will be working on my Twitter impulse control,” he added.
On Monday, Hammer wrote in a since-deleted Twitter post, “So touched by all of the celebrities posting pictures of themselves with Stan Lee… no better way to commemorate an absolute legend than putting up a picture of yourself.”
“If Stan impacted you life (ie. All of our lives) with his work, post his work that touched you the most,” he continued. “Posting a selfies makes his death about you and how cool you felt taking a picture with him.”
Morgan, 52, called out Hammer in a now-deleted tweet, writing, “Looks like you found a way to use others ways of mourning and their memories to draw some attention to yourself.”
The Walking Dead actor added, “You sound like a real a–hat.”
Reps for Hammer and Morgan did not immediately respond to PEOPLE’s requests for comment.
Some Twitter users also disagreed with Hammer’s view. “They… worked with him…?” one person wrote.
“Me…. too…?” Hammer replied.
A person asked, “what else u supposed to do when someone dies armie.”