The Belgium international left Anderlecht in the summer after receiving interest from a handful of clubs, including the Gunners.
Rather than move to the Premier League, the 20-year-old chose Monaco in a £22m deal after learning that Arsenal manager Arsene Wenger intended to keep faith with his current crop of players.
"I knew not much was going to change with Arsenal's squad," The Metro quotes Tielemans as saying. "Their management wanted to keep the same group of players together in order to finish high in the Premier League.
"I had to be honest with myself and take a look at the midfielders Arsenal have got. They are top-class players. I knew that I would not get many first-team chances with them, so I didn't give any more thought to joining them. I never said no to any club, but I made it clear where I wanted to go."
The midfielder has made seven appearances in all competitions so far this season and has scored one goal.