Giroud has been Frank Lampard's third choice striker this season, having played only 20 minutes in all competitions since September.
"He is frustrated, he wants to play more," Zouma told Canal+. "Like any football player, he wants to be on the pitch, but he is taking everything very calmly.
"He is a professional, he works hard in training. I have a lot of respect for the player he is. As someone in the dressing room, he is someone who gives advice to Tammy and Michy.
"He wants the best for the team, which is important, and it is why he is a good person."