Jones, 28, was removed from the UFC 200 main event late Wednesday evening after the United States Anti-Doping Agency informed him of a potential violation.
UFC president Dana White, in an interview Thursday with "The Herd" on FS1, said Cormier will fight this weekend but he didn't specify who his opponent will be. A heavyweight fight between Brock Lesnar and Mark Hunt has been elevated to the main event.
The USADA, Jones and his manager, Malki Kawa, confirmed Thursday that a banned substance was found in a sample Jones provided on June 16 but did not specify what it was. They also did not offer an explanation of how it appeared in his system.
Jones, who has been an advocate for more stringent drug testing, adamantly denied taking a banned substance.
"They found something in one of my samples that I have no clue what it is," Jones said. "I don't even know how to pronounce it. I've been taking the same supplements the majority of my career. I've been so outspoken about being against any type of performance enhancers. To this day, I'm extremely against performance enhancers.
"The whole thing sucks. Being labeled as someone who would cheat hurts more than anything else I've ever been through in my career."
According to Kawa, Jones has already requested that USADA analyze the B-sample of the positive test. Kawa was hopeful that those results could be made available as early as Thursday evening, although he acknowledged that the chances of a B-sample immediately clearing Jones' name "are very slim."
The USADA issued a statement Thursday saying it has been in communication with the Nevada State Athletic Commission about the case and that "Mr. Jones will be provided full due process under the rules."
Jones, who trains out of Jackson-Wink MMA in Albuquerque, New Mexico, said he introduced "a few things" to his body during this latest camp but described them as having "nothing to do with performance." He said he is compiling a list of all the supplements he has taken during camp to pinpoint the source of the positive test.
"My management team is very aware that everything needs to be documented leading up to a fight," Jones said. "I just know in my heart I would never take anything that would enhance me in any way, so I didn't feel the need to jot down anything. I didn't really think this could ever happen."
The UFC introduced a comprehensive anti-doping program in July 2015. Since the program started, Jones has submitted six samples, according to the USADA website. This is the first time Jones has tested positive for a performance-enhancing drug. He tested positive for traces of cocaine before a fight against Cormier at UFC 182 in January 2015.
Under the anti-doping program, a first-time offense for a performance-enhancing drug carries a standard two-year suspension. When asked what his reaction to a two-year ban would be, Jones said he would return.
"If I do have to sit out two years, I will definitely be back," Jones said. "I'm already thinking about the good that can happen. I'm optimistic. But man, at the end of the day, I'm a fighter. I'm a fighter. Even though I may seem broken up here, I'm not broken. I'm just really upset."
Jones (22-1) was scheduled to face Cormier (17-1) in a fight that would unify the light heavyweight championship. Jones originally won the title in 2011 and defended it eight consecutive times. The UFC stripped Jones of the belt last year after he was arrested on a hit-and-run charge in New Mexico. He pleaded guilty to that charge but avoided jail time.
Jones won an interim championship in a comeback fight in April.