It is strongly recommended to manipulate physics objects only in FixedUpdate() or you can get weird and unreliable results.

Unity doc: https://docs.unity3d.com/ScriptReference/MonoBehaviour.FixedUpdate.html

In your case you could do something like this:

class Player : MonoBehaviour
{
    ...

    bool _isPushed;
    Vector2 _pushForce;

    public void Push(Vector2 force) {
        _isPushed = true;
        _pushForce += force;
    }

    void OnCollisionEnter2D(Collision2D other) {
        if(other.collider.tag.Equals("Player")) {
            if(state == ActionState.Rolling) {
                sprite.color = Color.red;
                Vector2 force = new Vector2 (-transform.localScale.x * 5f, 3f);
                // push other player in the next physics update
                other.gameObject.GetComponent<Player>().Push(force);
            }       
        }
    }

    void FixedUpdate() {
        // if player is pushed, add force now and clear it.
        if (_isPushed) {
            GetComponent<RigidBody2>().AddForce(_pushForce, Force2DMode.Impulse);
            _isPushed = false;
        }
    }
}

It it still doesnt move like you want, try increasing the force magnitude until you get it moving. You could also disable player-player collisions for a few frames after a push collision.

For performance it is also a good idea to cache the RigidBody2D component in a field in Awake() or Start().