Pushed on whether there would be any ins or outs on Thursday, Mourinho added: "The information I have is no (nothing will happen)".
United's boss, about to begin his third season at the helm at Old Trafford, has cut a disgruntled figure during the summer, apparently unhappy with the club's transfer window activity.
United have been linked with several other signings, especially at centre-half , but Mourinho doubts deals will be done, telling reporters: "I'm not confident and the market closes today".
Mourinho also suggested he had not been given enough credit for guiding United to a runners-up finish in the Premier League last season, as he again suggested the negativity around the club was misplaced.
Mourinho was speaking at a 9am press conference and his words did not equivocally rule out the possibility of something happening. He was also asked a follow-up question to clarify that there would be no incomings or outgoings throughout the day.More news: Newcastle sign Japan's Yoshinori Muto, as Rafa Benitez expresses concerns
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"My view is that first of all is hard for me to believe we finished second", he added.
'Its hard for me to believe we finished second.
Mourinho has won three Premier League titles with Chelsea and two Champions League trophies as Porto and Inter Milan manager.
"He said: "[Sergio] Romero, he had a surgery after his injury, [Antonio] Valencia, he was injured in pre-eason, Marcos Rojo, he was injured in the World Cup, [Diogo] Dalot had a surgery in Porto at the end of April and he is not yet ready. In football you need time to work and players on the pitch to work and we didn't have that until now.
"The list that I gave you before of the injured players is an important list and today after training I will speak with that group of players (back from the World Cup) because everybody is different, physically and mentally, to see how available they feel".
Pre-season has clearly been a frustrating time for Mourinho, while a perceived lack of respect for leading his side to second spot last term has got under his skin.