"We are all shocked and deeply concerned for Elias' mother, as well as for Elias and his entire family," the Pirates said in a statement Thursday. "We are using all of the resources available at the Pirates and Major League Baseball to support Elias and his family during this incredibly difficult time.
"As we work with authorities on his mom's safe return, we will withhold further comment and ask that you please respect the family's need for privacy."
According to the Venezuelan website Meridiano, Diaz's mother was kidnapped in San Francisco, in the state of Zulia, on Thursday afternoon. One of Diaz's brothers was in the home when the abduction occurred, according to the report.
Kidnapping has been a significant concern in Venezuela. Some baseball players have been forced to move their families from Venezuela, and many hire security to protect those still in country.
In 2009, the mother of pitcher Victor Zambrano was kidnapped, and that same year, Yorvit Torrealba Jr., the son of Rockies catcher Yorvit Torrealba, and his uncle were kidnapped. Nationals catcher Wilson Ramos was kidnapped in 2011, rescued by commandos who swept into his captors' mountain hideout.
Last summer Tigers star Miguel Cabrera blasted the Venezuelan government and said he was tired of having to pay to protect his family from kidnapping.
Elias Diaz, 27, has played three years for the Pirates and became the regular backup to starter Francisco Cervelli in 2017. He hit .223 with one home run and 19 RBIs in 200 plate appearances but showed a strong arm and game-calling ability.
Pirates pitchers and catchers are scheduled to report to spring training Monday in Bradenton, Florida.