Video in tweet below.
Masked Helsingborg supporters ran on to the pitch when the full-time whistle blew on a match which saw the team kicked out of the Swedish top flight for the first time in 23 years.
The hooligans ripped the shirt off Helsingborg coach Larsson's son, 19-year-old striker Jordan Larsson, and punched him before security teams drove the crowd off the pitch.
Jordan did not speak to media immediately after the game, which Helsingborg lost to Halmstad 2-1, but his coach and father, who also tried to confront the supporters, said he was angry and frustrated.
“I understand their frustration and that's a reason why I myself walk up to them – because I'm angry, irritated and frustrated. When I realize the seriousness of what has just happened, that was probably not the smartest thing,” Larsson told a press conference.
Henrik Larsson speaking to reporters after the 2-1 defeat. Photo: Emil Langvad/TT
Larsson took over management of Helsingborg in 2014, the southern Swedish football town where he grew up. He played for the team before moving to Feyenoord in 1993.
“I know that I live and work in the city. I'll probably have to look over my shoulders both once or twice, but I have to take that. I am 45 years old. Make sure I don't go outside alone too much. I don't think it's very brave of them to mask themselves and come down and do what they do,” he was quoted by regional newspaper Sydsvenskan as telling reporters.
Asked whether he believed he had cause to fear for his own safety, he said: “It is entirely possible. I don't know. It's not a problem. I have plenty of dogs at home, so there are no worries.”
— Read Celtic (@ReadCeltic) November 20, 2016
Questions are already being raised about security at matches and the violent hooligan culture in Sweden, where several incidents have recently made global headlines.
For the 100th time: Swedish football has a serious problem. Fans storm pitch & try to take Jordan Larsson's shirt. https://t.co/YhGxu6ibGx
— Lee Roden (@LeeRoden89) November 20, 2016
In August, a match between Jönköpings Södra and Östersund was called off when a masked supporter ran onto the pitch and assaulted Östersund goalkeeper Aly Keita.
Two months prior, a fixture between IFK Göteborg and Malmö FF was abandoned after a supporter threw a firework at Malmö player Tobias Sana, who responded by throwing one of the corner flags in the direction of the person.
Jordan Larsson being escorted off the pitch. Photo: Emil Langvad/TT
The Swedish government has proposed making it illegal for supporters to hide their identity while attending games. It is not uncommon to see hooligan firms in the standing sections of Sweden's football grounds covering their faces with balaclavas or masks.
“The proposed legislations is a new tool for the police to stop those who are ruining the experience for all of us who only want to see a good match,” Sweden's minister for home affairs, Anders Ygeman, told The Local in September.