"It's a very bad thing, Twitter's role in that," Williams said. "If it's true that he wouldn't be president if it weren't for Twitter, then yeah, I'm sorry."
Trump's infamous use of the social media platform, which he joined in 2009 and gained a following before he ran for office, has separated him from past presidents. He now has more than 30 million followers.
The White House has defended his frequent use of Twitter as a mechanism for him to be closer to his supporters.
"I think that maybe I wouldn't be here if it wasn't for Twitter," Trump told Fox News in March.
Williams, who also co-founded Medium, told the Times he had a different vision for what the platform would be used for.
"I thought once everybody could speak freely and exchange information and ideas, the world is automatically going to be a better place," Williams said. "I was wrong about that."