The 33-year-old actress was lined up to play the female lead in the biopic, reported Variety.
"'Jobs' is still on the track to make its production date and actresses are already meeting for the part. However, no one knows the reason behind Portman parting her way from the film," a source said.
'Jobs' stars Micheal Fassbender as Jobs and Seth Rogen as Steven Woznaik. Danny Boyle is the directing the film. The script is written by Scott Rudin with Mark Gordon and Guymon Casady as producers.
The production is expected to start next year. Portman will be seen in Gavin O'Connor movie 'Jane Got a Gun'.