The former Seinfeld star plays a coffee shop barista who fantasises about a beautiful customer.
Brooke Burns, best known for her role on Baywatch, plays the customer in the five-minute clip.
Posted on Nickelback's official Youtube channel, the video is the latest release from the Canadian band's album Here and Now.
Nickelback recently announced a UK arena tour to begin this October.
Watch Jason Alexander in the video for 'Trying Not to Love You' below: