Producer John Schindler claims the friends conspired to block the U.S. release of "Don's Plum," which also stars Jeremy Sisto, Amber Benson, Kevin Connolly and Marissa Ribisi, E! Online reported Monday.
The 1996 low-budget indie flick has only been released overseas, E! said.
Shindler's suit filed Friday claims DiCaprio and Maguire "put the word out that they were opposed to any distribution of "Don's Plum" once they became Hollywood stars.
A similar suit filed by another producer was settled by the two stars out of court, E! said. However, they have refused to deal with Shindler.
DiCaprio and Maguire have a suit pending against Shindler, claiming they never intended the film to be released commercially.