Helsingborg's Par Hansson was knocked down by a Malmo fan who ran on to the pitch after the visitors opened the scoring through Rachid Bouaouzon in the 30th minute, Swedish national television reported on its website.
Referee Stefan Johannesson took the players off the field and 20 minutes later the top-flight Swedish league match was abandoned.
"It's just awful that this had to happen," he told Canal Plus TV. Hansson left the field with ringing in his ears after a firecracker landed near him before he was attacked by the fan.
Several Swedish clubs have recently had games disrupted by fireworks.
AIK Stockholm were handed a 3-0 defeat and fined 150,000 Swedish crowns ($23,670) after a league match at Syrianska in April was abandoned when the linesman was hit by a firecracker.
A female fan was injured during the derby between Gothenburg and GAIS while the Stockholm clash between local teams Djurgarden and AIK had to be stopped several times.
The problem has led the Swedish FA (SvFF) to ban pyrotechnics inside stadiums and instruct referees to halt play immediately if they see fireworks being used in the stands.
