Gazzetta dello Sport says the Serie A side cannot commit to buying the Armenian winger in the summer.
Mkhitaryan has an uneasy relationship with boss Jose Mourinho.
Inter are keen on the former Borussia Dortmund star and want him in their side.
But they cannot tell the Old Trafford club for certain that they can purchase him outright in the summer market.
It is believed Inter are handicapped by Uefa's Financial Fair Play regulations - which means their funds are limited.