Durust says United enquired about the availability of goalkeeper Fernando Muslera and defender Semih Kaya after this week's Champions League clash.
"Semih came from our youth academy. He is a valuable member of our squad," said Durust.
"We didn't set an asking price for him. He is indispensable at that moment.
"Muslera has the same value too. Both of them are in our future plans. We never want to sell them."