Neustift - France midfielder Blaise Matuidi pleaded with fans on Wednesday to stop jeering his international team-mate Olivier Giroud.
Some fans whistled and booed when Giroud's name was read out before Monday's 3-2 pre-Euro 2016 friendly victory over Cameroon in Nantes.
"I spoke with him after the victory over Cameroon. It's disappointing because Olivier gives everything for France," said Paris Saint-Germain midfielder Matuidi.
"He soaks his jersey (in sweat), as he should, he's an important player for us and we need him.
"This must end right now, we need support."
Matuidi's words of support echoed those of France coach Didier Deschamps at a press conference on Tuesday.
Arsenal striker Giroud scored France's second goal - his 15th in 48 internationals - against Cameroon.