Hackers trying to disrupt the Paris Olympics turned to disinformation campaigns when their electronic intrusions failed, a tactic that foreign adversaries could attempt to use against the U.S. elections next month.

Cybersecurity officials in France spent more than two years preparing for this summer’s Games, working with private companies and other parts of the government to shore up defenses. While there were constant cyberattacks from a variety of sources, none disrupted the Olympics, Vincent Strubel, the head of France’s cybersecurity agency, said in an interview this week.

Mr. Strubel said one activist hacking group, the Cyber Army of Russia Reborn, claimed that it would attack the water sanitation system in Paris to disrupt the swimming competitions in the Seine.

“We had to make sure that the attack could not happen from a technical side and then make sure they did not effectively make a fake claim,” Mr. Strubel said.

To counter the Cyber Army’s claims that the Seine water could be unhealthy, the French government both scanned for cyberattacks against the sanitation system and put out information about the water quality, officials said.

Ahead of the Games, the French agency worked with the sanitation infrastructure, strengthening its cyberdefenses, Mr. Strubel said.