Delaney's Nottingham side now sit third in Pool B
Munster came from behind to inflict an agonising 15-14 defeat on Nottingham in Pool B of the British and Irish Cup on Friday evening.
David Jackson scored the only try of the game for the home side, but they were left frustrated as fly-half Scott Deasy kicked 15 points for Munster.
"We are really disappointed," said director of rugby Glenn Delaney.
"Fundamentally because we lost on the scoreboard but we felt like we put a lot into that game."
He added: "We approached this game the right way with the right mindset. The game gets decided on small margins and today was one of those.
"We got a bit frustrated at times so we've got to look at some of the things we're doing against teams that are willing to go the extra mile in defence.
It was a great effort by everyone and a great day for the club but we will go away disappointed about the score
Nottingham director of rugby Glenn Delaney
"We're still in the hunt [to qualify from pool B] but we've got to get a win under our belt next week in this competition at home to Melrose."
It was a record crowd at Meadow Lane as 3,189 fans turned out, the first time Nottingham have broken the 3,000 barrier since relocating to Notts County's ground in 2006.
"It was a huge crowd," Delaney acknowledged. "They were really energetic and created a good atmosphere. It was a great effort by everyone and a great day for the club but we will go away disappointed about the score."
The Green and Whites took the lead through a James Arlidge penalty and things got even better for Nottingham as Munster flanker Tommy O'Donnell was sin-binned for a deliberate knock-on.
But they failed to make the extra man count, and Munster responded through a Scott Deasy penalty.
The yellow card was out again, this time sin-binning the Nottingham's Sione Kalamfoni and visiting captain Bill Holland for fighting.
The home side regained the lead just before half-time with a world-class try.
All Black Ali Williams stole the Munster throw at the line-out, and a wonderful Arlidge pass found Andy Forsyth who broke two tackles, off-loaded to Jackson who strongly powered through to touch down in the corner for his 100th cup point in Nottingham colours.
Munster took the lead for the first time in the second half after two Deasy penalties, before the fly-halfs exchanged two penalties each.
Nottingham pushed hard in the last 10 minutes, but Munster's defence was resilient as they took four points back to Ireland, leaving Nottingham with a losing bonus point.