This is the Russian argument. But the AP also tells us that Russia placed missile launchers in rebel-held territory in Ukraine. They cannot make Ukraine responsible for the air that Russian-backed rebels fire missiles through. That's just a displacement model.
It begins to sound like Russia knows it is on a sticky wicket.
The better response is that they thought it was a Ukrainian military plane flying in a war zone. In war, accidents happen. But then they have to admit they were supplying the rocket launchers and they don't want to do so because it destroys Putin's narrative.