Australia swimmer Mack Horton triggered uproar in China after branding rival Sun Yang as a "drugs cheat" before dethroning the Chinese star at the weekend.
That was followed by more vitriol on Sunday when athletes rounded on two-time Russian doping offender Yulia Efimova.
Efimova, cleared at the l1th hour to compete in Rio, was subjected to boos from the crowd while rival swimmers took verbal digs.
IOC spokesman Mark Adams said the organisation encouraged free speech and had no plans to take action.
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"Clearly we want to encourage freedom of speech," he said. "But on the other hand of course the Olympics is about respecting others and respecting the right of others to compete," he added.
"There is a line somewhere there, and each case is different of course, where people should be free to compete in tranquillity.
"So, yes, we would encourage people to respect their fellow competitors."
Adams said the IOC had no plans to take action over the Horton-Sun spat.
Rio 2016 spokesman Mario Andrada meanwhile suggested that some booing heard at venues was a symptom of Brazil's love for football.
"Booing is a part of the football culture," Andrada said. "It's part of the education that we need to help the Brazilians understand."
Adams added: "Brazilian fans seem to be pretty egalitarian. They seem to be able to boo athletes from many countries.