Pliskova, 15th in the world rankings, said on Twitter she suffered the injury during her quarter-final defeat by Iga Swiatek at the Stuttgart Open last week.
The Italian Open runs from May 9th-20th before Roland Garros, the second Grand Slam of the year, begins on May 28th. Pliskova's best result at the claycourt major came in 2017 when she reached the semi-finals.