Published Wednesday, 21 May 2014
Jackson will miss the tour in June due to injury. (© Presseye)
He has been battling the problem for some time, but the injury has deteriorated and he will miss next month's action against the Pumas.
A statement from Ulster Rugby said his injury will require rest and recuperation for Jackson to start next season fully fit.
Leinster player Ian Madigan has been confirmed as his replacement on the tour in Resistencia on 7 June and Tucuman on 15 June.
Jackson told UTV it was a frustrating end to the season for him.
"The initial scan didn't show up that I had the stress fracture, so I had a bit of shock on the way home yesterday," he said.
Coach Joe Schmidt said it was unfortunate for the fly-half. He said: "He's very disappointed, but at the same time he'll get a really good window to rest and recuperate. He'll be back ready to go at the start of next season."
There has also speculation over the playing career of Ulster and Ireland rugby star Stephen Ferris.
The back-rower has been troubled with an ankle injury over the last 18 months and returned to action for Ulster in March.
A spokesman for Ulster Rugby said no decision has been made on his future career.
© UTV News