He had attempted to return from the disabled list this week but suffered a setback Tuesday after having tightness in his calf on Saturday, per Jeff Wilson of the Fort Worth Star-Telegram.
The team will be conservative with the issue going forward, according to Grant.
Beltre began the year on the DL with a similar calf injury that limited him throughout spring training and the World Baseball Classic. However, he said at the time he "could play with it" and going on the DL was "difficult to accept," per Grant.
While this remains a concern, the 38-year-old has otherwise been relatively healthy throughout his extended career in the majors.
The Dominican star is in his 20th season at this level and has still appeared in at least 140 games in 11 of the last 13 seasons.
He also remains one of the most consistent hitters in baseball as he gets up there in age. Beltre has earned votes for Most Valuable Player in each of the last seven seasons, going to four All-Star games in this stretch.
The talented two-way player also has four Silver Slugger awards and five Golden Gloves in his career.
Obviously, this leaves the Rangers without a key component of their lineup when Beltre is unavailable.
Joey Gallo has been the starter at third base with the All-Star out and should remain in the role going forward with Jurickson Profar also getting some at-bats.