The German was targeted throughout Swansea's 2-1 Europa League defeat against Petrolul Ploiesti on Thursday evening.
Tremmel slammed the supporters responsible, saying "it's a football match not a laser-shooting game".
He added: "It was pretty much the whole game. It wasn't constant, but it was every few minutes someone pointed one at me.
"I think there were two or three different ones, from both stands. Once it hits your eyes you just can't see anything. They are powerful. I would see them flash across and then it would hit directly. It was bad. Obviously as soon as you move it stops because they would have to be a pretty sharp shooter to keep up with you moving.
"But it is in your head. You are trying to organise your defence at a corner, but you notice it happening and it is distracting. It is annoying."
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