Tesla's stock fell Monday after a British diver involved in the mission to save 12 Thai boys and their soccer coach said he is considering legal action against Elon Musk because the company's boss labeled him “pedo guy.”

Spelunker Vernon Unsworth had called a submarine crafted by a team of Musk’s technicians a “PR stunt.” Billionaire Musk suggested the vessel — made out of a SpaceX rocket part — could be used to assist rescuers in freeing the soccer team from a flooded cave system in Chiang Rai.

“He can stick his submarine where it hurts,” Unsworth said of Musk’s submarine idea in an interview with CNN. “It just had absolutely no chance of working. He had no conception of what the cave passage was like.”

In response, Musk launched a scathing attack on the cave explorer on Twitter. On Sunday, he said in a now-deleted series of tweets that he would release video footage of the cylindrical vessel sailing through one of the caves.

He then made the baseless claim that Unsworth was a pedophile, saying: “Sorry pedo guy, you really did ask for it.”

After another Twitter user challenged him on his remarks, Musk said: “Bet ya a signed dollar it’s true.”

Those tweets have since been deleted.

“I believe he’s called me a pedophile,” Unsworth told The Guardian newspaper. “I think people realize what sort of guy [Musk] is.”

When asked whether he would consider pursuing legal action against the Tesla CEO, Unsworth reportedly said: “Yes, it’s not finished.”

Representatives for Musk’s companies Tesla, SpaceX and The Boring Company were not immediately available when contacted by CNBC.

Tesla's share price fell more than 3 percent on Monday.

According to The Guardian, James Anderson, a partner at Baillie Gifford, Tesla's fourth-largest shareholder, said he would express his opinion on the situation with the automaker. The report did not provide any further details.

Musk has previously stated that it would sometimes be better to not respond to criticism on social media.

During a Q&A with Bloomberg, the entrepreneur said: "I have made the mistaken assumption — and I will attempt to be better at this — of thinking that because somebody is on Twitter and is attacking me that it is open season. And that is my mistake. I will correct it."