"The Forbidden Kingdom," which finished shooting in China last month, has been eagerly anticipated because it marks the first on-screen collaboration between Chan and Li - kung fu cinema's two biggest stars.
But the two actors have been playing down the film's potential appeal to Chinese viewers, saying it is targeted at a U.S. audience.
A news report carried on the Web site of China's state-run Xinhua News Agency quoted Chan as saying, "The movie I just shot with Jet Li, 'The Forbidden Kingdom,' actually isn't that great."
Chan was speaking at a news conference in the northeastern Chinese city of Changchun on Sunday, Xinhua said.
"'The Forbidden Kingdom' is a movie made for Americans," the report quoted Chan as saying. "Chinese viewers may not like it. If I say it's a good movie now, then many people will be filled with overly high expectations and be disappointed when they see the movie."
Solon So, a spokesman for Chan, said Tuesday that the action star could not immediately be reached to confirm the remarks.
Separately, Li made similar remarks, seen on Li's Web site on Tuesday.
"I hope everyone uses an open mind to watch 'The Forbidden Kingdom' and not invest too much expectation into my fight scenes with Jackie Chan," he said.
"The Forbidden Kingdom" is about an American teenager's fantasy journey to ancient China to rescue a mythological monkey king. The idea for the film originates from the classic Chinese novel "Journey to the West," in which a monkey king, a pig and a friar guard a Buddhist monk in search of religious texts.
Li plays the monkey king and a silent monk, while Chan plays another monk called T'sa-Ho.