Insigne reacted angrily to jeers from the Stadio San Paolo crowd during their 1-1 draw with Chievo Verona.
Benitez said: "Insigne is a young player and he knows he made a mistake. Many fans realised it's not positive to jeer the team. If we stick together as a group and support the players, it'll be better for everyone. It is important to create a positive atmosphere.
"We need to be more concentrated to avoid dropping more points."