PARIS— Elon Musk said Twitter is winning back nearly all of the advertisers who left since his takeover of the social-media company last fall, saying his goal for the platform was to “make it a positive force for civilization.”

Speaking before an at times raucous audience at a tech conference in the French capital, Musk Friday afternoon also gave a vote of confidence in his new Twitter CEO, Linda Yaccarino, saying that “almost all of the advertisers have said that, they’ve either come back or they said they will come back.”

Yaccarino, who previously led ad sales at NBCUniversal, “understands the concerns that advertisers have and I think will do a great job in addressing those concerns,” said Musk, who bought Twitter last fall, and leads electric carmaker Tesla and rocket company SpaceX.