Tesla Inc. says regulators are harassing Chief Executive Elon Musk over his compliance with a 2018 regulatory settlement that sought to restrict his use of social media.

The Securities and Exchange Commission is conducting unfounded investigations of Mr. Musk and Tesla, attorneys for the company say in a letter filed Thursday with a federal judge who oversaw the settlement. Tesla disclosed earlier this month that regulators sent a subpoena last year that sought information showing how the company and its CEO complied with the terms of the deal.