Fans invaded Old Trafford and went onto the pitch on Sunday as part of a protest against United’s owners, the US-based Glazer family.
Hundreds of fans managed to make their way into the ground, chanting “we want Glazers out.”
Large numbers of supporters had also gathered outside the stadium and there were clashes with police as they moved to disperse the crowd, with objects thrown at officers and horses.
Two officers were injured, with one “attacked with a bottle and sustaining a significant slash wound to his face, requiring emergency hospital treatment”, according to a Greater Manchester Police statement.
Assistant chief constable Russ Jackson criticised the “reckless and dangerous” behaviour of supporters involved in violent acts, saying it meant GMP had to “take officers from front-line policing and call in support from neighbouring forces to prevent the disorder getting worse”.
A United statement said: “Our fans are passionate about Manchester United, and we completely acknowledge the right to free expression and peaceful protest.
“However, we regret the disruption to the team and actions which put other fans, staff, and the police in danger.
“We thank the police for their support and will assist them in any subsequent investigations.”
The Premier League said while it understood the fans’ “strength of feeling”, it condemned “all acts of violence, criminal damage and trespass, especially given the associated Covid-19 breaches”.
Manchester City could have been crowned Premier League champions on Sunday had United lost the match.
The Premier League added that the “rearrangement of the fixture will be communicated in due course”.
Anger towards the Glazers has been reignited by United’s part in a failed European Super League (ESL) project, that collapsed within 48 hours last month after a backlash from fans, players, governments and governing bodies.
United and Liverpool were reportedly two of the leading drivers behind the project that sought to guarantee top level European football for 15 founder members every season without the need to qualify on the pitch.
In a rare public statement, United co-chairman Joel Glazer apologised to fans last month for signing up to the ESL.
“You made very clear your opposition to the European Super League, and we have listened. We got it wrong, and we want to show that we can put things right,” he said.