The Jets take on the Sky Blues in a bottom of the table meeting at Sydney Football Stadium and Milicevic and Wehrman both look like missing out following a training ground bust-up.
Culina admitted that the incident is not what the club needs as they strive to get back to form.
"The reason I took action, and both Nathan Tinkler, the owner, and Ken Edwards, the chairman, supported it, is because we want to set a standard of behaviour on and off the park,'' Culina told the Newcastle Herald.
"The incident was unprofessional. You do not want that from two of your senior players who have leadership roles in the club. We expect our leaders to act as leaders.
"It is not the first time. It happened a few weeks ago, therefore we have taken this action.
"It is a message to those two individuals, it is a message to the rest of the group and it is a message to our supporters, that we will accept nothing but the very best behaviour."