The 22-year old, whose side lies eighth in Serie A, said the team was not correctly set up, and added that it must now improve.
“Something had to change, as we didn’t have the right balance. All that counts is what is best for Roma,” he told reporters.
“Our all-attack style of play was our strength and also our biggest weakness. We must work hard to climb back up the table.”
Pjanic also played down rumors that he was close to leaving the Italian side, adding: "I have a contract with Roma and I’m happy, even if things aren’t going well. Anyone who wants me must talk to the club first.”
Barcelona and Pep Guardiola's Bayern Munich have been rumored to be interested in the Bosnian.