I am very familiar with LAX having flown in and out about 500 times. I would say that unless you are lucky, and traveling with virtually no luggage, your chances are not good to make this connection. (Can you get your AA boarding pass at your point of origin?) There is a fair amount of walking to get out of 7, into 3, and the distance around the airport is not insignificant. If you don't have any luggage you might want to walk from 7 back to 4 (regular AA terminal) then take the bridge to the parking lot, walk through the parking lot, and out the other bridge at 3. But you are talking about a 10-15 minute walk/run.