Peter claimed the title after beating Russian Oleg Maskaev on 12 March to earn a record of 29 victories and one defeat.
Klitschko is entitled to the bout having not lost the title since he first won it in April 2004, before his retirement.
Since then he launched an unsuccessful bid to become mayor of Kiev.
Klitschko's younger brother Wladimir retained his WBO and IBF heavyweight titles by knocking out American Tony Thompson in the 11th round on 12 July.
The pair's ambition is ambition is to hold all the different heavyweight world crowns, with Uzbekistan's Ruslan Chagaev currently the holder of the WBA version.