Who can play an elf? LARP's thorny issue

I play a dwarf when I larp, but I did not start out as a dwarf. People just automatically assumed I was a dwarf because I am shorter than average, have a full beard, are rather stocky/muscular, and was wearing more armor than average. I was wearing no dwarven racial costuming (the game requires specific bits of costume for each race) but based off the above information they assume I was a dwarf. I did switch later to playing a dwarf but at the time it was irritating, instead of looking at physical characteristics I recommend looking for cultural cues.

Whomever feels the urge - it's ROLE PLAY. Although it would be funny to see Legolas picket a LARP event with a sign that says "My culture is not your costume" in Elvish script.