Ljajic, who also plays for Italy's Fiorentina team as a midfielder, was suspended from the Serbian team after telling coach Sinisa Mihajlovic that he would not sing the national anthem before the team's game against Spain Saturday out of principle and did not plan on changing his position, RIA Novosti reported.
The Serbian Football Federation said Monday that refusing to sing the national anthem violated a "point of agreement" in Ljajic's contract.
Ljajic, 20, will be invited back if he sings the anthem in the future, the federation said.
Earlier this month, Ljajic was caught up in another controversy when Fiorentina coach Delio Rossi slapped him as he returned to the bench after being substituted in a Serie A game.
Video of Victoria’s Secret models trying to 'twerk' hits Instagram
Wisconsin business offering 'therapeutic cuddling' forced to close