Supplanted at second base by rookie Jason Kipnis, Cabrera saw his playing time diminish recently. Cleveland acquired Minor League outfielder Thomas Neal, who has been optioned to Triple-A Columbus.
Neal is currently on the Triple-A disabled list with a left hand contusion.
Indians general manager Chris Antonetti was not available for comment.
Cabrera, 36, opened the season as Cleveland's starting second baseman, but struggled offensively as the summer wore on. In 91 games for the Indians, Cabrera hit .244 with four home runs and 38 RBIs.
By joining the reigning World Series champion Giants, Cabrera's chances of keeping his impressive postseason streak alive increase. The veteran infielder has reached the playoffs in six of the past seven years with the Red Sox, Angels, White Sox, Twins and Reds.
Cleveland promoted Kipnis -- a highly-touted second base prospect -- from Triple-A Columbus on July 21. With Kipnis manning second a majority of the time, Cabrera became expendable for the Tribe. Cabrera was under contract for $1 million and he will be eligible for free agency this offseason.
Neal, 23, was hitting .295 with two home runs, three triples, 13 doubles and 25 RBIs in 60 games for Triple-A Fresno. Along the way, he posted a .351 on-base percentage with a .409 slugging percentage. Neal is now on Cleveland's 40-man roster.
San Francisco selected Neal in the 36th round of the 2005 First-Year Player Draft.