The 17-year-old Aamer returned with figures of 3-24 off his seven overs in his sixth one-day appearance while fast bowler Gul bagged 3-28 off eight overs. Off-spinner Saeed Ajmal also picked up two for 16.
While chasing, Pakistan faced some serious problems as Gavin Tonge picked up four wickets to leave them struggling at 76 for five.
Pakistan also started on a poor note with both the openers Kamran Akmal and Imran Nazir making five runs each before returning to the pavilion. Former skipper Shoaib Malik and comeback man Mohammad Yousuf also got good starts but couldn't convert their identical 26 to a big score.
But Akmal and Afridi held their nerves with their 58-run unbroken partnership for the sixth-wicket and as Pakistan romped without suffering any more damages.