Pjanic has expressed his disappointment at the sacking of Zeman, who oversaw a run of five Serie A games without a win, insisting that it would not have been an easy decision for the club's directors.
"It was certainly not an easy decision for our directors to make," Pjanic wrote on his Facebook page.
"I am so sorry it ended this way and I wish the coach all the best.
"Now we must turn over a new leaf and I ask all of you to be united so we can bring normality back and emerge from this situation for the good of our Roma."
Aurelio Andreazzoli has been installed as temporary coach of the Rome side.