Polar bears can be aggressive when needed but most polar bears will not attack humans.
Unlike most other bears polar bears prefer to get away from the situation and not engage in a fight or attack with a human or any other bear or other animal.
Polar bears can be dangerous though so you need to keep your distance from them just in case but most times polar bears will not even come close to you or want to attack you.
I've been near polar bears before in the wild and they never bothered me.
Just keep your distance and don't make yourself seem like a threat to them and they will usually leave you alone.