Unless Air France has rules that are airline-specific for flights to the US, then that shouldn't be a problem. But it's not an FAA issue. I have been in the cockpit on flights to the US during takeoff in Europe, during the flight, during landing in the US, and also the other way around. That was on LX, several times, and the cockpit crews explained to me that there was no rule against that. Restrictions exist for flighs to/from the UK (and I wuold suppose also Israel), but apparently not the US: Air France does allow cockpit visits and I have been in cockpits several times, although not to the US:

If memory serves me well there was a delegation of kids visiting the A380 cockpit on a recent flight to the US, but I might be wrong and it was on the return flight to Europe.

In any case, no har min asking, and there is a 90% chance that you'll be allowed to visit the cockpit.