"It was just so disappointing missing out on that that I had to think about retirement," Williams told reporters. "I spoke to the people closest to me, I didn't want to retire or anything like that.
"But I felt like it was something that I should've thought about and seen where I was at with club and international football and life in general.
"I did give that a thought, but then I decided I wanted to keep doing it anyway."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Williams said that he had met with new Wales manager Ryan Giggs and his backroom staff earlier this month to help them get familiar with the team.
Giggs, who succeeded Chris Coleman in January, will take charge of his first game when Wales face China in the opening match of the China Cup tournament later on Thursday.
(Reporting by Aditi Prakash in Bengaluru; Editing by Peter Rutherford)
