Fred was hit by a missile as he went to take a second-half corner in the 2-1 Premier League victory at the Etihad Stadium, where a fan appeared to aim a monkey gesture at the Brazil international and team-mate Lingard.
A 41-year-old man was arrested on Sunday in connection with the allegations, before being bailed by police pending further investigation.
“We have spoken with the boys, of course,” Solskjaer said. “I think they are the same as me – that this isn’t how it should be in football.
“But what we can do is go out onto the pitch next time and prove that we are all equal.
“So, it has been a tough couple of days I am sure for Jesse and Fred, but we just have to help the other people as well to understand their behaviour is important.”