After a goalless 90 minutes, both sides netted their first six penalties before Frankie Musonda saw his spot-kick saved by stopper Jonathan Bond.
Jones said: "I thought it was a good entertaining game. I am not pleased we lost the game on penalties, but they're eighth in League One, they made very few changes from their side that played against Villa [in Posh's 3-1 win a Villa Park in the Emirates FA Cup] and play week-in, week-out.
"We made ten changes, we've had equal chances and I think it was a good entertaining game. It just shows where we are. We've got a real strong squad and we've made changes and we've been able to more than compete with a side that is eighth in League One.
"The players who have come in have not so much given me food for thought, we've got a strong squad and we needed to test those and they got tested. I thought they were excellent tonight.
"We're aspiring to be a League One team next year and I thought we more than matched them and tonight I thought we had some real good performances from the young ones. I thought Akin Famewo was outstanding. Jack Senior as well.
"We're a young side and I thought they were excellent. Some of the ones who need game time, Sheehan, Cook, Lawson and Pelly, were excellent as well."