Molina initially injured his foot on Friday while running out a double. He missed games on Saturday and Sunday against the Cincinnati Reds but had returned to the lineup on Monday against the Philadelphia Phillies.
The nine-time Gold Glove winner said he "had trouble moving around,'' according to manager Mike Shildt.
The Cardinals recalled catcher Ali Sanchez from their alternate site in a corresponding move.
The 38-year-old Molina, in his 18th season with the Cardinals, has had a strong start to the season at the plate, hitting .323 with five home runs and 14 RBIs.
The nine-time All-Star is leading the team in both batting average and RBIs and is tied for the team lead in home runs with shortstop Paul DeJong.
Andrew Knizner is expected to get the bulk of the work behind the plate in Molina's absence.
The Associated Press contributed to this report.