Einarsson, 26, has been training with the Leeds squad but cannot sign for the club until the transfer window reopens.
Leeds have appealed on the grounds that Einarsson is now technically unemployed during December.
Einarsson told BBC Radio Leeds: "I'm unemployed and they're not allowing me to work. If Fifa says it's OK then I get the green light."
If Fifa rejects Leeds' appeal Einarsson will have to wait until January 1, when Leeds are at home to Crewe, to be in with a chance of featuring in a match.