Pirates were beaten 17-16 in the British and Irish Cup, their third defeat by the same opponents in the space of five weeks.
"I know we can produce a lot better than that," Cattle said.
"To run them close is good, but when you reflect on that performance and what we could have controlled, we could have come away with a win."
London Irish, who have won all their matches since being relegated from the Premiership last season, lead second-placed Pirates by nine points in their cup pool with only 10 still to play for.
But Cattle says there is no reason his side cannot secure one of the three places in the quarter-finals for the best runners-up.
"If we get two bonus point wins from Connacht and Ospreys we'll be in with a shout of a runners-up spot," he told BBC Radio Cornwall.
"We're at the midpoint of the season in the Championship, we're five points off third, two points off the top four, so for us we're in a good place.
"Just because results have gone against us in recent weeks doesn't make us a bad team overnight."
Cornish Pirates coach Gavin Cattle says his side wasted the chance for a first win over London Irish this season.