The Red Devils have donned a pride-themed warm-up jersey and walk-out jacket in the last two seasons as part of the Premier League's Rainbow Laces campaign, in a show of support to the LGBTQ+ community.
This season, United had planned for their players to don a similarly-themed jacket to head out in prior to their clash against Everton on Sunday.
However, according to The Athletic, Morocco international Mazraoui told his teammates that he was not prepared to do so, citing his Muslim faith as the reason behind this.
As a result, the team then decided that no players would wear the adidas jacket, in order to avoid the £15million summer signing being singled out for criticism.
The outlet also reported that not everyone in the United dressing room was happy with this decision.
Read More on Man United
'Devastated' Shaw posts emotional statement as Man United react to latest injury setback
Arsenal vs Man United has turned one-sided after being greatest Premier League rivalry
A United statement read: "Manchester United welcomes fans from all backgrounds, including members of the LGBTQ+ community, and we are strongly committed to the principles of diversity and inclusion.
"We demonstrate these principles through a range of activities, including support for our Rainbow Devils supporters' club, and campaigns to celebrate our LGBTQ+ fans and combat all forms of discrimination.
"Players are entitled to hold their own individual opinions, particularly in relation to their faith, and these may sometimes differ from the club's position."
Captain Bruno Fernandes did wear the rainbow armband, reflecting the club's support for the campaign amid controversy over Ipswich skipper Sam Morsy refusing to wear it.
Most read in Football
Julen Lopetegui on the brink of West Ham sack with three possible replacements waiting
'Devastated' Shaw posts emotional statement as Man United react to latest injury setback
Bizarre admin gaffe sees Lucy Bronze barred from entering pitch as substitute
West Ham eye up former Champions League manager as Julen Lopetegui fights to save job
Meanwhile, Crystal Palace captain Marc Guehi is in hot water for writing religious messages on his rainbow armband despite a warning from the FA.
More to follow.
Andy Goldstein urges Jim Ratcliffe to reverse £26 Manchester United ticket increase