Ye, 16, has faced questions since she took five seconds off her personal best and more than a second off the world record in the 400m individual medley. In the last 50m, she swam faster than the men's champion Ryan Lochte.
John Leonard of the of the World Swimming Coaches Association this week called the Chinese swimmers gold medal performance disturbing and unbelievable.
Mark Adams, an IOC spokesman, said that critics of the swimmer should back down and accept that athletes often produce dramatically improved performances in the Games.
"We need to get real here. These the world's very best athletes competing at the very highest level, he told reporters at the Olympic Park.
"We have a very, very strong drug testing policy. We are very confident that if there are cheats we will catch them."
Asked if the Chinese swimmer had passed the mandatory drug test for medalists, he replied: "We would only start to comment if we had any adverse finding. At the moment I'm not commenting. Draw your own conclusions."
He admitted that speculation about performances was inevitable, but added: "Let's give the athletes the benefit of the doubt."
Scientists and former athletes also defended the Chinese teenager's performance.
Prof John Brewer, a board member of UK Anti-Doping and director of sport at the University of Bedfordshire, said:
The drug testing procedures in place at the London 2012 Olympics are extremely rigorous and the storage of samples for 8 years after the Games makes doping an very high risk strategy. We should not be surprised by exceptional performances since Gold medal winning athletes are inevitably different to the rest of us due to their talent, training and lifestyles.
It's also worth remembering that China has a vast pool of talent to choose from due to the size of its population, so we should not be too surprised when an individual with exceptional talent emerges.
Duncan Goodhew, Olympic Village Deputy Mayor, and a gold medallist in the men's 100 metres breaststroke in the 1980 Moscow Olympics, said competitors were innocent until proven guilty - and that there were always "incredible improvements" in performance at large sporting events such as the Olympic Games.
"There are always incredible improvements in any large sporting event such as the Olympic Games, and of course, in terms of that, innocent until proven guilty," he told ITV Daybreak.
"I think it is very destructive and very irresponsible of anybody to accuse people until they are proven guilty."
