The hooligan, identified under Dutch privacy laws only as Wesley van W., ran onto the Amsterdam Arena pitch on Dec. 21 and tried to kick goalkeeper Esteban Alvarado from behind. The Costa Rican keeper spun around and parried the attack before twice kicking the hooligan as he lay on the turf.
Prosecutors had sought a 10-month prison term at Thursday's trial.
A police judge at Amsterdam District Court also ordered the 19-year-old to report to police during all Ajax, Alkmaar and Dutch national team matches for the next two years, according to reports.
Two months of the prison term were suspended, meaning Van W. will only have to serve them if he commits another offence in the next two years. Calls to the court and prosecutors seeking confirmation of the sentence went unanswered Thursday evening.
The match was halted after the attack with Ajax leading 1-0 after Alkmaar coach Gertjan Verbeek ordered his players off the pitch. The match is to be replayed in full next month.
Esteban was sent off for kicking Van W. but authorities later retracted the red card.