Is it muttar for a man to trim his eye brows if they grow a little long and unkempt?
My understanding of your question is that you want to shorten the hairs so they shouldn’t look so overgrown. It is permitted to trim them since you are not doing it in a way that women trim their eyebrows, so it isn’t lo tilbash. Additionally, and it is being done not in order to beautify yourself as women do, but in order to avoid embarrassment, therefore it is permitted..
Avnei Yoshpe 4-91, Ohel Yackov ( Lo Tilbash) pg. 143 in the name of R’ Nebenzahl shlit”a, and pg. 145 in the name of Shevet Hakeosi.