Morrison, 20, has been in scintillating form this season. He has scored five times in 12 appearances for West Ham and been the focal point of their struggling side.
Allardyce said: "It's a long way between now and the World Cup squad being picked. He's going to have to continue his improvement to be - or have any chance of being - considered for that squad of players going to the World Cup.
"Its a nice goal for him, I don't think there is anything wrong with that dream. Without dreams you can't be successful trying to achieve those dreams. He can make that dream a reality.
"Not too many people reach their ultimate goal in life. When you have that chance, if you are dedicated enough in your time on and off the field then you can get there."
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