Flynn's Exiles take a 2-0 lead into their Sky Bet League Two semi-final second leg in Gloucestershire following an impressive display at Rodney Parade on Tuesday.
But Ball, who was last month promoted from academy coach at Rovers to interim manager after Mark Cooper was sacked, said ahead of Sunday's return that Forest Green had already planned their Wembley final travel next week.
"l'd probably say it shows his inexperience as a manager to say that," Flynn said.
"One thing people know about me is that I'm not arrogant and I don't get carried away with things."
Flynn has promised Newport will not sit back on their two-goal lead at the New Lawn.
"One thing I definitely won't be doing is parking the bus," said Flynn, who has captain Joss Labadie available again after injury.
"The pressure's on them to get the next goal. If they don't and we do then that's the tie over.
"I've heard all the talk about a 2-0 lead being a dangerous score. But look at the stats about how many teams come back from that score to win and it's very low.
"It gets emphasised that much more when it does happen, so I'm not buying into the mind games of the 2-0 scoreline.
"That's for the people who want to stir it up and have some hope. But we've kept seven clean sheets out of 10 games, so let's hope we make it eight out of 11."
Ball insists the tie is far from over and wants the returning Forest Green fans to create a "bear pit" atmosphere after the vocal nature of the 900-strong Newport crowd.
He said: "Tuesday was as poor as the lads have been, certainly since I've been in charge.
"But it was one of the best performances I've seen Newport put in. I think it's fair to say that we can't be that bad again, and I hope they're not that good again.
"We have to score three goals, and if they score first, that doesn't change.
"The message is very clear – score three goals and you have a chance of going to the promised land.
"Wembley is the holy grail – no matter where you're from or what age you are. To play on that hallowed turf is a dream."
Morecambe will defend a 2-1 lead in Sunday's other semi-final after their first-leg win at Tranmere on Thursday.
Shrimps boss Derek Adams said: "It was a fantastic result for us, but as we know it's just the first leg and we have another leg to go.
"It's difficult, we have got to get the players prepared for Sunday in a short space of time."
Interim Tranmere manager Ian Dawes said: "The onus is on them now. We know that we have got to win there and take the game to them.
"We have got to make sure that we have that mindset and we've got to manage the next 90 minutes of the game."