Roethlisberger told KDAA-TV in Pittsburgh that he regretted using his weekly radio show to criticize Brown's effort and route running last season. Brown was traded to the Oakland Raiders in March.
"I took some heat and deservedly so for some of the comments on that show and especially towards him," Roethlisberger told the station, according to ESPN. "I genuinely feel bad about that and I'm sorry."
Roethlisberger specifically apologized for comments made after the Broncos' Week 12 loss in Denver. Roethlisberger said on his weekly radio show that Brown should have run a flatter route on a ball the Broncos intercepted.
"If that's what ruined our friendship, I'm truly, genuinely sorry about that," Roethlisberger said.
Brown responded on Twitter on Monday afternoon, calling the veteran quarterback "Two face."
Pittsburgh missed the playoffs for the first time since 2013.