Speaking after seeing the Irish side avenge a quarter-final defeat at Castle Park two years ago with a bonus-point win, Griffiths said: “We were lacklustre but to use that as an excuse would be disrespectful to them because they did a job on us.
“We had a great opportunity to score early doors but Paul Jarvis threw out a bad pass and had it gone 14-0 it could have been a different ball game.”
Added Griffiths, who made seven changes: “I’m disappointed that we’ve lost at home and that we haven’t maintained our winning sequence, but I’ve no qualms about the result because they beat us fair and square.
“Having said that we helped them along the way and 14 of their (second half) points came from interceptions which was something we’d spoken about at half time.
“As I say, we wanted to maintain the momentum after ending 2016 with successive Championship wins and I wanted the people who haven’t been playing regularly to take their opportunity and unfortunately that didn’t happen.
“I don’t believe that they are a better team than us, it was just on the day it wasn’t the Championship and it looked like that.
“We went side to side with the ball but they kept 14 players on their feet across the field and a full-back.
“We kept trying to play but we came up against a brick wall today and speaking as a former (Wales) defence coach, all credit to them.”
Skipper Michael Hills came off as a precaution with a tight Achilles tendon.