Yes, there is an easy way for a number of zoom lenses:
https://www.pentaxforums.com/forums/6-pentax-dslr-discussion/161684-da18-250m...ion-works.html
With the DA18-250mm, the simplest and most effective way to stop zoom creep on the 18-250mm is to use a rubber wristband: e.g., you can buy these for $2 at charities. These rubber wristbands are the perfect size. Place the rubber wristband around the lens, on the camera side (see photo below). The friction of the rubberband along the zoom ring is enough to strop completely the creep. It is very effective and long lasting. The cost is minimum and the outcome an asset if you disklke creep. A small point: you cannot use the zoom lock but you really do not need it. Lastly do take care that the rubber band is no wider than the distance between the zom ring and the camera.
It should work with DA18-135mm. Mine does not have zoom creep so I did not try.
Hope that the comment will help.