Cloth.useGravity  

// Dont use gravity on this cloth regardless if is Interactive or Skinned.

transform.GetComponent(Cloth).useGravity = false;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        transform.GetComponent<Cloth>().useGravity = false;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        transform.GetComponent[of Cloth]().useGravity = false