Ljajic has a year left on his contract at Fiorentina and the Viola are reported to be keen to retain the Serb, who has recently been linked with a move to Manchester United.
Speculation has also claimed that Milan are showing an interest and Galliani is keeping an open mind regarding the prospect of signing Ljajic.
"He could become our target, but in this moment he's a player with a contract," Galliani told Sky Sport Italia.
Galliani is also prepared to let Robinho fulfil his wish of rejoining former team Santos, providing the two clubs can agree on a fee.
He added: "Robinho wants to go back to Santos. We will see if we will find an agreement.
"In the last few hours, there has been a further approach, but there isn't an agreement yet.
"We will start looking for another striker only when Robinho leaves. We have a good team and five strong forwards."