Remy is back with parent club Chelsea for rehab.
Pardew said: "(He has) a tear in his thigh. It is an area where recovery is difficult. We have to be careful. We are so disappointed because he looked great. It was a very innocuous moment on the training ground.
"Sadly that happens. Fortunately we have enough cover to cope without him for this period. Seven or eight weeks he is going to have to be out. But we have had good negotiations with Chelsea."