Newport were under the cosh for much of the first half but went in front through Conor Washington's 23rd-minute goal. Harry Worley wrapped up the points by lashing home at the back post after 70 minutes to complete the win.
"It was a disappointing loss against an opponent that played very tough and fought for everything and fair play to them," Tisdale said. "We had the lions' share of possession, but it is about what you do in the penalty box.
"You get judged on your execution and what you do and there is no point saying: 'what if?' You get judged on what you do and we missed the target too often and we didn't defend our six-yard box well enough and that's the reality of the day unfortunately.
"I haven't watched it back, but I don't think the players did what was asked of them. I think they need to be better. I am not talking about how hard they worked or how they passed it, because a lot of players showed they were good players here. But it's about the team being effective and doing what I ask them to do and if they don't do it, I will change it.
"We didn't play badly and our players looked like they were on their game. But I was not happy with the way we played in both goal areas."