The AFL has written to all 18 clubs warning them against unsportsmanlike behaviour after slapping Melbourne's Lachie Hunter with a $1500 fine for his bizarre boundary-line antics.

During the second quarter of Melbourne's win over Hawthorn last week, Hunter left the Demons' interchange area and rushed towards the boundary line outside of the interchange gates.

Hunter gestured towards a Hawthorn player who had just taken possession on the wing, either to distract the player or make him think that Hunter was in play and a chance to tackle him.

The AFL took a dim view of the incident, labelling it as unsportsmanlike and dishing out a fine to Hunter.

"Melbourne and Hunter have accepted the AFL's sanction," the AFL said in a statement.

"The AFL has written to clubs today to remind them that such actions by players stationed in the interchange area are not appropriate."

Hunter was a part of the Bulldogs' 2016 premiership side and he notched 173 games for the club across 10 seasons before moving to Melbourne at the end of last year.

The 28-year-old has played all nine games for the second-placed Demons this season, averaging 20.7 disposals and two clearances per game.