My guess is probably nothing you can do. The seeds need to develop on the plant. But you can plan for next year!
Although leaving the pods doesn't weaken the plant, it is good to remove them if you are not trying to save the seed because if the seed develops and falls to the ground, they may germinate and eventually the new iris plants will be competing with the original plants---and they may be inferior blooms. The new ones may even crowd out the originals.