Eriksen enjoyed a terrific spell with Brentford during the latter part of last season as he returned to football following his collapse at Euro 2020.
The Dane’s arrival helped the Bees arrest a mid-season slump and ultimately secure comfortable survival in their maiden Premier League campaign.
Eriksen only signed on a short-term deal until the end of the campaign and despite being offered an extended contract that would have made him the best-paid player in the club’s history, the former Tottenham man instead opted to join Manchester United on a free transfer.
The 30-year-old enjoyed a torrid return as United were hammered 4-0 at Brentford on Saturday afternoon, with the midfielder booed and serenaded with chants of “You only went for the money”.
“I understand fans, how they can react,” Frank said. “Personally, I think we as a club should show class, respect and integrity throughout every action we do. That’s what I try to do every single day.
“I think we need to remember it wasn’t every fan that did it. But I think that any player coming back - it doesn’t have to be Christian, it could be Neal Maupay or Ollie Watkins - the first time we should applaud them when their name is read out.
“Of course, there is the banter when you can sing a little bit, but booing a player? That’s not class, that’s not me. If fans want to do that, I won’t say it’s fine, but I would never do it.”