The Red Devils ended their pre-season campaign with a 1-0 defeat at German champions Bayern Munich on Sunday.
Javi Martinez headed home a second-half winner to give Bayern victory in a match they dominated.
“My CEO knows what I want and I still have a few days to wait and see what happens,” Mourinho said on MUTV.
“The other clubs who compete with us are really strong and already have fantastic teams. Or they are investing massively like Liverpool, who are buying everything and everybody.
United have so far signed three players this summer – Brazil midfielder Fred for £47m, Portuguese defender Diogo Dalot and third-choice goalkeeper Lee Grant.
They open the Premier League season against Leicester City at Old Trafford on Friday.
Former chief executive Peter Kenyon said on Sunday he believes Mourinho needs to find a way of “working out” his issues with executive vice-chairman Ed Woodward.