This was really unfortunate timing as Mako was still low on energy and if he had to fight, he would be at a big disadvantage against them.
However, he didn't have any other option other than to fight because he couldn't just escape and leave his friends behind. His hands were covered in flames as he was prepared to strike immediately if it happened to be a beast that wandered into the cave because the beast would become aggressive as soon as it saw him.
But if it was a person, Mako would only give them one chance to state their intentions, and if he even felt the slightest hint of danger from them he wouldn't hesitate to launch an attack.
