Affleck was spotted with the tattoo on the set of "Live By Night" in December after fans caught a glimpse over the summer.
"It's awful!" Lopez exclaimed.
"I mean, would tell him that. I would tell him, 'What are you doing?' It has too many colors. His tattoos always have too many colors. They shouldn't be so colorful. They should be cooler, I don't know."
Lopez's remarks came just days after Vanity Fair released an interview with Affleck's estranged wife, Jennifer Garner.
The 43-year-old actress opened up about their split in the issue and shared similar sentiments about the actor's tattoo.
"You know what we would say in my hometown about that? 'Bless his heart,'" Garner said. "A phoenix rising from the ashes. Am I the ashes in this scenario?"
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Affleck and Garner announced their split in June but have yet to officially file for divorce.
The estranged couple share three children and were reportedly friendly when they saw each other at the Vanity Fair Oscar party on Sunday.
"They spoke for a while and then went about their own business with the people they came with," a source told E! News.
"Jen smiled and Ben was very normal ... Their facial expressions were not awkward at all. It seemed like they were more like friends."
Lopez and Affleck were together over a year before calling off their engagement in 2003.
The singer released her eighth studio album, "A.K.A.," in 2014, and serves as a judge on the 15th and final season of Fox reality competition "American Idol."
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