The 1-0 defeat, in Rovers' last game at Belle Vue, was Nottingham Forest's second in a row although they remain top of League One.
"We need to lift the spirits a little bit but we want nobody feeling sorry for themselves and no negativity," Calderwood told the club website.
"The momentum has stalled and now Boxing Day at home is a very important game.
"But we will enjoy the victory and we will enjoy promotion."