Pathfinding with dynamic objects?

Hello guys!
I have seen tutorials which shows that how can I make a Creature avoid the obstacles, calculate a path etc.
But those tutorials didn't really showed how can I make a Creature avoid other moving creatures.

So my question is this:
Do I have to solve this problem on my own, or is it built in Unity? (or available in the asset store for free)

Example for my problem:
I command 10 melee soldiers to attack a rounded tower but instead of standing around the tower (so everyone can attack at the same time) 3 soldiers attack the tower, while the 7 others are just walking in place. (Because the others block the way for them)

Thank you for your further help and sorry for my English!

 

Now I am working with Unity's NavMeshAgent, but it didn't solve my problem with the local collosion avoidance.
My code is this: if a creature starts attacking a tower (so he is in attack range), I disable the Agent, and enable the Obstacle so the others who are not yet attacking will avoid them, and they will select a new path to the tower.
I paused the scene, and there were 3 creatures attacking, and they were obstacles. And there was 1 creature who wasn't attacking, and so he was agent. But for some reason he didn't look for a new path, instead he was "pushing" his ally like in the previous times.

I got it finally. I check "Curved" at the Obstacle component.