This is a very strange situation (see attached..), Is there anything one can do to run / defend / fight back?
There's no specific tactic to recommend in your situation - as in any situation in FTL, you'll either fend off the attacker (until one of you is destroyed / able to flee) with whatever weapons / abilities you have left... or you won't, and you'll get to try again.
There are some general tactics that can help you to avoid getting into this situation next time:
Consider diversifying your weapons portfolio - lasers, flak cannons and beams don't run out of ammunition.
If using explosives, always buy at least one missile whenever you get the chance - and try to ensure that you've always got scrap to spend on them.
Same goes for fuel - always buy it when you can. In my experience trying to maintain around 10 fuel at all times is a reasonable aim on Easy difficulty.