The chief executive and chairman of HBO has admitted to tasking staff with creating a fake Twitter account to attack TV critics.
It comes after Rolling Stone reported that Casey Bloys created a "secret army" to hit back at negative coverage.
Mr Bloys apologised to the TV critics who were targeted at a press event.
He said it was done during a period where he was "working from home and doing an unhealthy amount of scrolling through Twitter".
"And I come up with a very, very dumb idea to vent my frustration," he said at the HBO event in New York on Thursday.
In the text exchanges, Rolling Stone reports that there was one occasion when a TV critic tweeted about the HBO period drama Perry Mason: "Dear prestige TV. Please find some way to communicate male trauma besides showing me a flashback to the hero's memories of trench warfare."
Mr Bloys was seemingly annoyed, according to text messages reviewed by Rolling Stone, and sent the tweet to Kathleen McCaffrey, HBO's senior vice president of drama programming.
He then reportedly drafted a response for an employee to tweet: "A somewhat elitist take. Is there anything more traumatic for men (and now women) than fighting in a war. Sorry if that seems too convenient for you."
The tweet was not sent in the end but other messages were reportedly later sent from fake accounts.
Speaking on Thursday, Mr Bloys said that six tweets over an 18-month period was "not very effective" but apologised to those targeted.
"I do apologise to the people who were mentioned in the leaked texts," he said.
He added that he now sends direct messages to journalists to express his feedback.
The BBC has approached HBO for a comment from Mr Bloys.
The text message exchanges between Mr Bloys and Ms McCaffrey are reportedly part of material being gathered for a lawsuit filed against individuals including the two, as well as HBO, by a former employee named Sully Temori - who claims to have had his job wrongfully terminated.
He alleges that he was harassed and faced discrimination after disclosing a mental health diagnosis to his bosses.
He also alleges that he was asked to perform tasks including creating fake online accounts to respond to critics of HBO shows.
As well as sending the tweets, Mr Temori told Rolling Stone he had also left anonymous comments on some Deadline articles about HBO series featuring other users' negative comments, at the instruction of Mr Bloys.
Lawyers for HBO requested that Mr Temori's lawsuit be dismissed. They told Rolling Stone that HBO denies "each and every allegation."
A statement from HBO said it "intends to vigorously defend against Mr Temori's allegations. We look forward to a full and fair resolution of this dispute. In the meantime, we wish Mr. Temori, a former HBO employee, well in his future endeavors."