According to a statement from Lincoln Center, the singer's doctors "have advised her to take complete rest due to a lower-back injury sustained early this year."
The performances will not be rescheduled; ticket holders may exchange their tickets, donate them to Lincoln Center, or request a refund.
Lieberson canceled a spring recital tour because of similar problems, and will miss a scheduled appearance in Mahler's Eighth Symphony at Tanglewood on July 8.