Major League Soccer has increased New York Red Bulls midfielder Kaku's suspension from one to three games and fined him for reckless conduct for kicking the ball into the sideline stands that struck a fan.
The league announced the increased penalties Wednesday.
Kaku, whose full name is Alejandro Romero Gamarra, initially received a red card and an automatic one-game suspension for the incident late in the Red Bulls' game against Sporting Kansas City on April 14. He served the one-game ban Saturday against New England.
The MLS Disciplinary Committee also found the Red Bulls and Sporting in violation of the mass confrontation policy during the April 14 game and said both clubs will be issued a warning for their first violation.
Kaku tweeted an apology after the game, writing: "I want to take the time and apologize for my actions during tonight's match. As a competitor, I was frustrated with myself and took out my frustrations in a way that is not acceptable. I love this game and would never want to disrespect it."
In a gesture of goodwill, many Red Bulls players approached the stands to check on the fan immediately after the game.
The Associated Press contributed to this report.