Ole Gunnar Solskjaer’s side finished sixth in the Premier League and face a Europa League qualifier on July 25, unless City beat Watford in the FA Cup final on Saturday.
The early start to the season would disrupt their preseason schedule that is already in place and includes friendlies in Australia, Singapore, China and Cardiff.
United are set to play Tottenham in Shanghai on July 25, the same day as the potential Europa League second qualifying round first leg.
If City can complete the final leg of their domestic treble, United will enter the Europa League in the group phase.
If not, they will have to play on six consecutive Thursdays – in the second qualifying round, third qualifying round and play-off round — before being entered into the draw for the group stage on August 30.
The first group games will be played on September 19.
The squad are due to report back for Carrington for the start of preseason training on July 1, before flying to Australia on July 7.
Unitedare due to play Perth Glory in Perth on July 13 before a game against Leeds United, also in Perth, on July 17.
From there, they will fly to Singapore to play Inter Milan on July 20, before facing Tottenham in Shanghai on July 25 and AC Milan in Cardiff on August 3.
The new Premier League campaign begins on August 10.
