Zeman was axed on the weekend.
"All that counts is what is best for Roma," Pjanic told Bosnian media after a friendly with Slovenia.
"We are coming off a difficult moment. Our objective was to be among the top teams, but now we are far away, so it was only normal that something had to change.
"I hope the situation can change with the new Coach, because this side has the quality to do well. We didn't have the right balance. We had the best attack, but also the worst defensive record.
"Our all-attack style of play was our strength and also our biggest weakness. We must work hard to climb back up the table."