Giroud featured for the full 90 minutes in France's 1-1 draw with Paraguay in Nice, in which the sides traded goals in the final eight minutes, but Ribery was not involved as he continues to battle a back injury.
French FA president Noel Le Graet stressed at the end of last week that Ribery was in "no danger" of missing the World Cup following a scan on the problem, but Giroud said his teammate is growing increasingly concerned with France's opener against Honduras on June 15 growing nearer.
"He has started to become angry," Giroud is quoted as saying by L'Equipe. "He is worried and concerned about his situation. We must help him hold on and be patient. When I'm injured for three days, I lose it. It is on the eve of the World Cup."
France coach Didier Deschamps was tight-lipped so as to not fuel speculation on Ribery's availability for Brazil, conceding there was "nothing new" to add following the Paraguay match.
Loic Remy, who was deployed on the left in Ribery's absence, said France's missed opportunities early in the fixture at the Allianz Riviera cost them a result.
"We started very well, we had a lot of opportunities we did not finish and in the end we were punished after opening the scoring," Remy said. "This kind of meeting should enable us to rectify before the World Cup. We must be vigilant and not concede a goal in that way."