The 24-year-old was a key player for the Giallorossi as they finished second to Juventus in the last campaign.
The Rome outfit are expected to challenge for the Scudetto once again this season, and Pjanic has revealed that he turned down a move away from the club this summer to help them win silverware.
"I've received many offers but I decided to stay with Roma because I want to win the Scudetto," he told Sport.ba.
"And because of Rudi Garcia, with whom I have an excellent relationship and who shares my ideas on football."
Pjanic has spent the past three seasons at Roma since his move from Lyon in 2011.