Rogge said Saturday that no action would be taken against individuals if they wear clothing, for example, made by a competitor of official London Games sponsors.
He said the IOC and local organizing committee would not be heavy-handed after head organizer Sebastian Coe told a British radio station on Friday that a person probably would not be allowed into an Olympic venue wearing a Pepsi T-shirt because soft drink rival Coca-Cola was a main sponsor.
"Common sense would prevail," Rogge said, but warned that Olympic sponsors' rights would be protected and a "blatant" attempt at ambush marketing would result in intervention by the IOC and the local organizing committee.
"Our position is very clear. We have to protect the sponsors because otherwise there is no sponsorship and without sponsorship there is no games," Rogge said. "However, you have to be balanced and reasonable and I am sure that is going to be the case."
Rogge added that individual cases would not be pursued by the police.
"LOCOG will have a very, I will say, subtle approach," he said. "But if there is a blatant attempt at ambush marketing by another company or by a group of people with commercial views, then of course we will intervene."
FIFA acted at the World Cup in 2010 in South Africa after more than 30 women showed up at the Netherlands' opening match wearing orange mini-dresses emblazoned with the name of Dutch brewery Bavaria NV.
The brewery has made a habit of ambush marketing stunts at the World Cup.
Olympics organizers are similarly vigilant about protecting the rights of sponsors like McDonald's, Adidas, Cadbury and Coca-Cola, which pay as much as $100 million each to be official sponsors during each Olympic cycle.
The logos of competitors are banned from venues, and under a special Olympic law passed by the British Parliament, businesses can be barred from using words and phrases — including "London 2012" or even gold, silver and bronze — that suggest an Olympic association.
"Common sense will prevail and LOCOG will work with common sense," Rogge said.