The Magpies striker is refusing to wear a shirt emblazoned with the Wonga logo as his Islamic beliefs forbid lending money for interest.
Cisse is yet to train alongside his St James' Park team-mates since returning for pre-season and was forced to sit out Newcastle's trip to Portugal.
It has been suggested that the Senegal international may have played his last game for the club, with Alan Pardew faced with the prospect of having to offload his most potent attacking weapon.
PFA chief executive Gordon Taylor is, however, still hopeful that a compromise can be reached which suits all parties.
He said: "We're working with Newcastle United, Papiss and his advisor to achieve a satisfactory settlement.
"We're consulting experienced people within football used to dealing with equality issues who are Muslims."