The Cod Army’s decision adds to Pompey’s postponement frustration this term.
Kenny Jackett’s side have already seen scheduled league meetings with Rotherham, Southend and Bury either rearranged or scrapped.
Now the Fleetwood postponement has become the fourth at this early stage of the campaign.
It means Pompey will have gone 19 days without a League One fixture, prior to hosting Rochdale at PO4 on November 23.
And Kenny Jackett admitted the 13th-placed Blues’ momentum could be impacted by the extended break from third tier action.
The manager said: ‘There have been a number of times this season where we have gone two-and-a-half weeks without a league game.
‘It’s tough then for momentum and builds up pressure.
‘But it is what is is.
‘By the time Rochdale comes around, we have to be ready.
‘It’s unusual and it’s happened quite a few times this season.
‘We have to make sure we try to learn from it, stay as consistent as we can.
‘We need to tick over in the meantime.’
Fleetwood boss Joey Barton was critical of Sunderland for postponement a scheduled fixture earlier in the season because of international call-ups.
But Jackett believes the Cod Army will have their reasons for calling off the scheduled Fratton Park fixture.
‘You’d have to ask Joey Barton what he feels,’ said Jackett.
‘For most managers, it’s what’s going on at your own club, mainly.
‘Whether they have injuries as well or just a straight three.
‘They’ll have their own reasons.’