NO! NO!! I used expanded metal to pen a puppy. He ended up with a badly cut nose.
Sheet metal will rust unless you paint it. Even then, the weather will eventually get at it. However, it is tougher than aluminum.
Without pics, I can't be sure what the dimensions are. Here are two options:
1. Standard galvanized chicken wire. Easy to apply, flexible, see-through, cheap, relatively weather resistant.
2. You can obtain a roll of 25" wide roof valley flashing and apply it with zip ties. This allows you to pickup the wrought iron in various places for strength. You can overlap the runs to get more coverage. Plus, it weathers well.
Can't promise it will look all that good. Have you considered electrifying the fence? (Kidding)