About 80,000 musicians from U.S. and Canada took part in the "Listen Up" campaign that kicked off Thursday, said Ray Hair, president of the American Federation of Musicians.
"People who love the movies know that musicians are the heart and soul of the film," Hair said.
The group wants to end the outsourcing of musical work overseas.
"We need that money for our economy. We need that money to support our citizens, to feed our families and not for it to run off to foreign countries," Hair said.
Los Angeles City Councilman Paul Koretz said state and local leaders are working to keep productions in the city and country, but more needs to be done to entice industry decision makers to use local musicians.
"I don't know whether these companies save a few bucks, but it's the tiniest, tiniest piece of their bottom line. We shouldn't let them get away with it," Koretz said.