"I didn't want to enter free agency in the first place, but it was a one-way door given to me by the GM to leave Houston," Williams told KRIV-TV in Houston, referring to general manager Rick Smith. "I want the fans there to know entering free agency was not my decision."
Williams signed a six-year, $100 million contract with the Bills this past summer. He has 3½ sacks but has been bothered by a wrist injury. He had a surgical procedure last week, during Buffalo's bye, to repair the wrist.
The two-time Pro Bowl selection told reporters Wednesday that his "wrist feels great" and that getting back into the weight room "lightened his spirits."
"I have a little something extra to prove," Williams said when asked about his slow start to the season.
KRIV reported that Smith declined comment.
"The way things ended, I definitely feel like it was kind of a rough and all-of-the-sudden goodbye. There's some things that I'm definitely uneasy about, the final decision making that happened there. It was just the way it was handled," Williams told KRIV.
"At the end of the day I'm just extremely excited to be able to be in this position and come back and play."
Selected by Houston first overall in the 2006 draft, Williams had 53 career sacks in six seasons to set the Texans' franchise record.
Information from The Associated Press was used in this report.