Fans have "the right to express their opinion" as long as it is "peaceful" Manchester United interim manager Ralf Rangnick has said.
His comments come as a protest is expected against the club's ownership ahead of their Premier League match against Norwich on Saturday 16 March.
Supporter group The 1958 Group say it is the first of a number of "relentless" protests against owners the Glazer brothers, claiming the club is "a mess".
But, they have said protests would not be "another Liverpool", where fans broke into Old Trafford before a behind-closed-doors Premier League game against Liverpool in May 2021, forcing the fixture to be postponed.
Fans will meet at the Tollgate in Stretford on Saturday morning before marching to Old Trafford.
They plan to remain outside the stadium until the 17th minute of the match, marking one minute for each year of the the Glazer family’s ownership.
There was a heavy security presence around United’s Carrington training ground on Friday after around 30 fans congregated with an anti-Glazer banner before the gathering was dispersed by the police.
"We know that football is a game of passion and emotion," Rangnick said.
"I think we can all understand our supporters are disappointed both with where we stand in the table but also the performance which we showed against Everton.
"But I believe our supporters are one of, if not the, best in England and as long as they protest in a peaceful way and as along as they still support the team in the stadium I think they have the right to express their opinion. I can understand they have been disappointed."
Regarding Friday’s protest, 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."
On 2 May last year, Liverpool’s visit to Old Trafford was called off after a planned peaceful protest - estimated to be 1,000 strong - escalated, with fans breaking into the stadium and causing damage.
Feelings against the Glazer family have risen again since the failed European Super League project, but the sense of frustration has also increased amid United’s onfield struggles.
The Red's 1-0 defeat at Everton, coupled with Tottenham’s 4-1 win at Aston Villa, has left United six points off the top four with seven games left to play, although Rangnick insisted the side had improved since he took over from Ole Gunnar Solskjaer in late November.
The Florida-based Glazer family have owned United since 2005 and have overseen a sharp decline in performances and results in recent years.
The record 20-time champions of England have not won a Premier League title since Sir Alex Ferguson’s final season in charge in 2012-13 and no kind of silverware for five years.