Enemy direction going crazy after collision

Well, this is my first time here friends! I wrote a simple code for moving an enemy. But when he collides with anything he seems to lose direction (following the player).

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Mouthless_Behaviour : MonoBehaviour 
{
	public Transform target;
	public float rotationSpeed = 0.1f;
	public float movementSpeed = 1.0f;

	// Use this for initialization
	void Start () 
	{
		
	}
	
	// Update is called once per frame
	void Update () 
	{
		if (target != null)
		{
			transform.position += transform.forward * Time.deltaTime * movementSpeed;

			var rotation = Quaternion.LookRotation (target.position - transform.position);
			transform.rotation = Quaternion.Slerp (transform.rotation, 
                                                     rotation, Time.deltaTime * rotationSpeed);
		}
	}
}

If he collides with anything he change his direction and stop following the player.
Here a GIF from this issue: Here!

I found the solution, just stopped the Rigidbody rotation since my enemy rotation is by code :smiley: something like this:

rigidbody.angularVelocity = Vector3.zero;