Wasim finished with 3-21 as West Indies -- sent in to bat -- were left struggling at 31-4 before they added 72 more runs on a slow bounce pitch at Sheikh Zayed Stadium.
Marlon Samuels, who top-scored with a 59-ball 42 not out, added 37 for the unbroken sixth-wicket stand with Kieron Pollard, who made an unbeaten 16.
Pakistan had already sealed the series after winning the first two matches by nine wickets and 16 runs respectively, both in Dubai.