The Portuguese's relationship with striker Anthony Martial appears to have broken down completely after the Frenchman left the tour early to attend the birth of his son in Paris, only to then fail to return.
Mourinho's position was in stark contrast to England manager Gareth Southgate's much-praised decision to allow Fabian Delph to leave the World Cup finals to be with his wife at the birth of their child.
Do you think Mourinho is the right coach for United?
"As I was saying to the players, some of my players will be in an unbelievable condition", he said.
He has been linked with a move away from Old Trafford and it is understood manager Jose Mourinho is willing to sell the France forward.
"More or less I know (my best team)", the United boss told beIN SPORTS.
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But he said reaching a detailed trade agreement with the European Union would likely prove hard . He said the administration is now focused on resolving the steel and aluminum tariffs.
"My players [have been] incredible in their effort but we have more effort in front of us", said Mourinho after goals from Alexis Sanchez and Ander Herrera secured the win over Real.
They open the 2018/19 Premier League season with a home clash against Leicester City on August 10.
He also recently had a rant about the quality of some of United's youth players who were part of the club's pre-season tour of the USA while a few of the club's first team stars are still on holiday.
"He is still very young and has to adapt to this style of football and what we ask of players".
Mourinho - who having guided United to Europa League and League Cup success in his first season - delivered nothing last term.
"We go to Munich in a few days and we start the Premier League in nine days".