The striker joined the Elland Road outfit in August 2012, but has fallen out of favour in recent months with just one appearance since October.
Diouf still has six months remaining on his contract, though McDermott has insisted that the player could leave during the current transfer window if a suitable bid is made.
"I told him I'm trying to build something here," the Leeds manager told Sky Sports. "If there's an opportunity that's right for him then, yes, he can go. But if not, then he's here."
Defeat for Leeds on the weekend against Leicester City leaves them six points off a playoff place.