Pompey kept on pouring forward in search of a route through the stubborn Charlton defence.
But they were unable to turn their dominance into many clear-cut chances and were beaten 2-0 at Fratton Park.
Goals from Jonny Williams and Chuks Aneke ensured the organised Addicks returned to London with all three points.
But Andy Cannon has demanded the Blues keep their heads held high after seeing their winning run come to an end.
He said: “We dominated most of the game and controlled the possession, but didn’t have the clear-cut chances.
“On Tuesday we scored four goals, but this time around it just seemed like one of those frustrating days for us.
“If we’d have scored early on, then I think we might have gone on to get a few more and then it’s a different story.
"It’s frustrating for us, but you can’t afford dwell on the performance too much. We’ll keep looking forwards."
“It felt like we were going to get something, but it wouldn’t open up for us and they were able to counter. It was a kick in the teeth.
“We’re working hard as a team and everyone’s grafting for each other. It’s good to see we’re all fighting.
“Now we’ve got to look on to Tuesday because we’ve got another tough game straight away at Lincoln.
“It’s frustrating for us, but you can’t afford dwell on the performance too much. We’ll keep looking forwards.”
Cannon has been used in a deeper midfield position alongside skipper Tom Naylor in the past few weeks.
He said: “I’ve played that role before at Rochdale, so it’s nothing new for me. I’m hoping I can keep my spot in the team.
“I suppose there’s less pressure on me to get the goals and assists – although I set up two goals on Tuesday night!”