The ban on Barca transfers covers the next two windows, but Mamic said that because the deal has already been agreed Halilovic will leave for the Camp Nou this summer as planned.
"I called the Barcelona board and got an assurance that the sentence does not affect the transfer of Alen Halilovic," Mamic told Sportske Novosti.
"Everything is fine, there is no need for speculation. Alen will move to Barcelona after this season, that is for sure. The contract is signed and you can be sure that nothing unusual will happen."
The 17-year-old has been capped three times by Croatia.