Diarra earned his first call up to the under-21 team in August 2002 for a friendly match against Cyprus. He made his debut in the match as France cruised to a 1–0 victory. Diarra featured regularly within the team as France attempted to qualify for both the 2004 UEFA European Under-21 Football Championship and the football tournament at the 2004 Summer Olympics. France failed to qualify for both competitions, which resulted in the end of Diarra's youth career. He appeared in 10 competitive matches with the team and scored his only goal in a 3–1 UEFA U21 tournament qualification win over Israel. In December 2003, Diarra was called up to the Mali national team to participate in the 2004 Africa Cup of Nations. Diarra turned down the opportunity to represent the nation of his parents in order to continue his career with his home country France.
