Velocity Movement & Physics Interactions by Rigidbody2D

I'm creating a platformer game at this time. The best movement system I've found for the player is by direct manipulation of the velocity. However, this poses a problem. Whenever a physics interaction occurs, my code will simply overwrite it on the x axis. That is not the desired effect. I'm wondering if anyone has any ideas as to how to maintain the velocity controlled movement system, as well as allow for physics reactions to coexist.

I'm open to other movement systems that may work as well as this one. The control you get through direct velocity control is something I would hate to lose.

 protected void SetVelocity()
         {
             float curSpeed;
             curSpeed = 100f * Time.deltaTime * speed * Mathf.Asin(theta);
             GetComponent<Rigidbody2D>().velocity = new Vector2(curSpeed, GetComponent<Rigidbody2D>().velocity.y);
         }