Osbourne expressed regret in a statement regarding his filing in U.S. District Court in Manhattan, alleging he had unsuccessfully tried for three years to convince his fellow Black Sabbath founding member to share the band's name, E! Online reported Friday.
"Tony, I am so sorry it's had to get to this point by me having to take this action against you," Osbourne said.
After Osbourne left the heavy metal band during the 1980s, Iommi continued to tour with Black Sabbath without the singer for most of the '90s.
Osbourne alleges in his lawsuit he is entitled to portion of the proceeds from those 1990s performances. The British rocker is also seeking a 50 percent stake in all profits generated as a result of the trademark name.
E! Online said Osbourne, who joined Iommi and bassist Geezer Butler for a Black Sabbath reunion in 1997, also maintains his vocals were the key to the band's success.