The 39-year-old said: "For me, I always believe in Wenger."
"Everyone knows the task is to qualify for the Champions League again next season. The team has been too inconsistent this season to do much more."
Pires also defended striker Olivier Giroud, who has scored nine goals in 30 appearances since joining from Montpellier in the summer.
He added: "The people need to give Olivier time. I know he is a good player."
"It is very difficult to adapt from French football and everyone needs time, even Thierry [Henry] did in the first half of his first season at the club."
"I would tell supporters to relax, Olivier will score goals."