Wednesday, Dunham wrote as a guest editor for The Hollywood Reporter's Women in Entertainment issue.
In a letter, she apologized to actress Aurora Perrineau.
Dunham had previously for publicly disputed Perrineau's account of being sexually assaulted by "Girls" writer Murray Miller.
Last November, Perrineau revealed she had filed a police report accusing Miller of raping her in 2012.
Dunham admitted that she had lied when when she claimed she had "insider information" that would support Miller's innocence.