The IOC executive board and the athletes' commission said after a joint meeting they supported the rule under which more than 40 athletes will not be able to compete in 2012 in London.
Merritt, the 400m Olympic champion in 2008, is serving a 21-month ban for using a male enhancement product. The ban expires in July and he is eligible to compete at the world championships - but not at the Olympics, which the American intends to contest before the Court of Arbitration for Sport.
"The rule applies. It shows the full resolve of the IOC in the fight against doping and demonstrates that Olympic athletes serve as role models worldwide," said IOC vice-president Thomas Bach of Germany, who heads the IOC juridical commission.
Bach did not want to speculate on a possible CAS verdict, but said the rule had the full backing of the athletes' commission and was no second punishment as implied by its critics.
"It is not a sanction. It is a condition of participation. The IOC is governing the Olympic Games and has the right to put conditions for participation," Bach said.
The strict IOC rule was decided upon in 2007 and went into effect a year later ahead of the Beijing Games.
