The 17-year-old winger has caught the eye of scouts from a number of European clubs with his performances in Serbia.
Portuguese side Sporting CP also made an offer in the winter, reportedly worth up to €2m for him.
Red Star are braced for new bids with Kurir reporting that West Ham are ready to pay €1.7m and Olympiacos willing to offer €1.5m.
Pantovic shone in this season’s UEFA Youth League and made his first-team debut for Red Star in an 8-0 win over FK Trepca last October.
Since then, he has made five appearances in the Serbian league as a substitute.
Though naturally a left winger, Serbia youth international Pantovic also plays on the right flank.