The Stoke man was hurt towards the end of Tuesday morning's session in Malahide as he and the rest of the squad continued their preparations for Friday's World Cup qualifier in Sweden.
However, goalkeeping coach Alan Kelly later revealed the medical staff are confident there is no lasting damage.
Kelly said: "It's a bit of a bang. He sort of stepped across the ball and Shane Long came in and hit the nerves on the outside of the leg, so it's really just an impact injury.
"I think he'll be okay. It's not a twist or anything like that, just an impact injury.
"After the initial burning went, he got up and got on with it. He's a tough lad, Jon."
Walters had lengthy treatment on the pitch, but was able to walk back to the team coach and the squad headed to their Portmarnock base at the end of Tuesday morning's session.
He will be assessed further but again, Kelly is hoping his injury is minor.
He said: "Obviously after something like that, he would be assessed, but he was okay. Just talking to him there, he seemed to be getting over the initial shock of it, really.
"He'll get a bit of ice and as I say, he's a big, tough lad, Jon, and I think he will be okay."
The Republic faces the Swedes at the Friends Arena in Stockholm and then take on Austria in Dublin next Tuesday evening with all three sides looking to win the race for second spot in Group C behind leaders Germany.