The 22-17 defeat to an Ian Madigan-inspired Leinster was Glasgow's first defeat in eight games, with the losing bonus point only keeping them above Ulster in second place by points difference.
Having taken a 17-6 lead on the half-hour, Glasgow looking on course for victory until eight minutes from time when Madigan touched down to nudge Leinster ahead, confirming victory with a 77th-minute penalty.
"We are desperately disappointed not to get a win," said Townsend after the game.
"The weather played a factor. The team that played into the wind held possession. I thought we did a lot of good things in attack when we did have that ball."
The Warriors lost 31-3 to Munster in the return leg at the start of December, and Townsend will expect a better performance from his side.
"To have led for most of the game, it is really disappointing to pick up only one point," he added. "We've got a very tough match against Munster. We've got to bounce back with a win."
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