Pretorius was ruled out of the tournament in Australia due to a left- thumb fracture sustained during the third T20I against India.
Titans fast bowler Lizaad Williams has been called up to replace Jansen among the travelling reserves.
Jansen got the nod over Andile Phehlukwayo, who remains among the reserves.
Proteas squad – Temba Bavuma (c, Lions), Quinton de Kock (Titans), Reeza Hendricks (Lions), Marco Jansen (Warriors), Heinrich Klaasen (Titans), Keshav Maharaj (Dolphins), Aiden Markram (Titans), David Miller (Dolphins), Lungi Ngidi (Titans), Anrich Nortje (Warriors), Wayne Parnell (WP), Kagiso Rabada (Lions), Rilee Rossouw (Knights), Tabraiz Shamsi (Titans), Tristan Stubbs (Warriors).
Travelling reserves: Bjorn Fortuin (Lions), Andile Phehlukwayo (Dolphins), Lizaad Williams (Titans).
