The Italian club have long admired Martial, who has scored 21 goals in an excellent season at Old Trafford.
But the French striker's market value of around £60million - and the fact he is contracted to United until 2024 - would prove a stumbling block.
But Calciomercato.com says Inter could take advantage of United's pressing need for a new centre-half to strike a deal.
Inter value Slovakian defender Milan Skriniar at around £58million, meaning they'd only have to pay a small amount of money for Martial.
A centre-back to partner Harry Maguire is a summer priority for United with Skriniar, 25, one potential target.