In a bowl, combine egg, rice, onion, parsley, salt and pepper.
Crumble beef over mixture and mix lightly but thoroughly.
Shape into 1-1/2-in. balls.
Arrange on a trivet in a 6-qt. electric pressure cooker.
Combine soup, water and Worcestershire sauce; pour over meatballs.
Lock lid; close pressure-release valve.
Adjust to pressure-cook on high for 10 minutes.
Quick-release pressure.
Let stand 5 minutes before serving.
If desired, serve with rice and top with chopped parsley.