I was in Paris this week and went to this restaurant
http://www.relaisdevenise.com/
It is not near the Louvre, but about 15 minutes walk from Arc de Triumphe. It is very close to Port Maillot metro station.
It is a very popular place, we had to queue outside for over half an hour on Monday night, but it is worth it.
It is a little weird as they only have one dish - steak. When you get sat down you are asked how you want your steak, medium or well done. You are then brought a salad and when you've eaten that your steak arrives. It is in a sauce and served with french fries. It is really, really nice. Then comes the surprise, when you've eaten your steak the other half of it arrives (they've been keeping it warm!), along with more french fries. There are about a dozen desserts to choose from.
I went here as I had a personal recommendation, and I have no problems recommending it to other people.