Police were dispatched to Manchester United's Carrington training facility following a protest by a small group against the club's owners, the Glazer family.
The group was seen at noon (UK time) on Friday, with one placard stating "Glazers Out."
Additional demonstrations are planned for Saturday's Premier League match between the Red Devils and Norwich City.
A club spokesperson said: “There was a small and peaceful protest outside the Carrington training ground today.
“We respect the opinions of fans and remain committed to strengthening our engagement with them.”
A statement from the protest organizers
“A fish rots from the head down and, under the Glazers since 2005, Manchester United has slowly become a stinking carcass.
“That said, there is still no excuse for the fetid performances consistently churned out by a playing squad that, as one of the bookies’ favourites for the title back in August, tends to under-deliver as much as it overpaid.
“Fans have had enough of the Glazers’ rewards-for-failure culture. Whilst the occupying regime thrives off the financial returns still delivered by mediocrity, supporters are entitled to expect players would have a bit more professional and personal pride than is too regularly being shown.
“That they don’t is indicative of their ACTUAL regard for the fans and the club’s history: one on the level of the contempt of the Glazers.
“No one is interested in their pathetic post-defeat Twitter sob stories anymore — they’re as meaningless as Joel Glazer’s pledges to liaise with supporters (ignoring his recent sops to handpicked stooges).
“Its (sic) long past time for these obscene-wage thieves to deliver so, as with the Glazers, they need to get out of the club.
“If that means coming back in August and the new manager playing the youth team, so be it.”
This is not the first time United supporters have taken to the streets to protest the club's owners. In April 2021, they were forced to postpone their home match against Liverpool when a huge number of protestors made their way onto the pitch.