"They're looking into it and we'll probably hear pretty soon," Nelsen said Tuesday, referencing the MLS. "I would say, as a guess, he probably might get a suspension."
Jackson was yellow-carded in the 50th minute for an apparent elbow as players jostled in the buildup to a free kick in Saturday's 1-0 win over D.C. United.
Nelsen said D.C. United midfielder Davy Arnaud was goading Jackson.
"He shouldn't have retaliated but I can understand it," he said of the Brazilian.
But Nelsen says he isn't about to shackle Jackson.
"He just wants to win, the guy. That's all he wants to do is he wants to win. He'll learn through experience, maybe there's better ways to do it.
"But I'd rather have guys who are wanting to win than little sheep out there. I understand we've got to tell him there's certain rules and regulations we've got to adhere to.
"But there's a fire in Jackson that I really like and appreciate and he brings a lot of energy to this club."
Toronto travels to Utah this weekend to play Real Salt Lake. And Nelsen was quick to point to Real Salt Lake forward's Alvaro Saborio's weekend foul on A.J. DeLaGarza of the Los Angeles Galaxy.
Saborio got a yellow card for the late challenge, with Galaxy players suggesting it should have been red.
With Real Salt Lake already suffering a glut of injuries at forward, Nelsen did some campaigning Tuesday to reduce the RSL strike force by one more.
"That could have broken his leg," Nelsen said of the Saborio challenge. "So if Jackson gets suspended, then you'd like to hope that a guy who's nearly broken a guy's leg is probably going to get suspended as well.
"But I don't know, you never know. I don't make those rules."
Jackson himself said he did not think a suspension is warranted, calling the incident "something that happened in the moment."
NOTES — Midfielder Jeremy Hall and striker Jordan Hamilton were both back in training Monday after recovering from injury ... Nelsen says signing Canadian international winger Issey Morgan Nakajima-Farran is just a matter of time