To understand why Virat Kohli was not suspended, we need to take a look at Article 2.12 of the ICC Code of Conduct, under

Virat Kohli was fined 20% of his match fee and received a demerit point for an altercation with Australian debutant Sam Konstas in the fourth Test in Melbourne. This incident adds to Kohli's history of ICC penalties,

Check the history of some famous penalty and fine impositions on India batter Virat Kohli by ICC for breaching Code of Conduct.