The 19-year-old suffered a 'grade 2 ATFL tear' at training, according to a statement on the club's website.
Margeman is expected back in the new year along with fullback Rheece Evans and midfielder Morne Nel.
Former Mamelodi Sundowns defender Evans hurt his groin in a loss to SuperSport United in late November, while Nel is making his way back from surgery.
Ajax finished 2017 with a 1-0 loss to Kaizer Chiefs in Durban on the weekend leaving Stanley Menzo's side in the relegation zone with 13 points from 14 games.
The Urban Warriors will resume their fight for survival against Maritzburg United at Cape Town Stadium on January 5.