Pakistan's newest sensation Usman Shinwari took 5-34 in seven overs to wreck Sri Lanka to 103 all out in 24.2 overs before Pakistan achieved the paltry target in 20.2 overs losing just one wicket at Sharjah stadium.
The win gave Pakistan their sixth 5-0 whitewash and ninth consecutive win since winning the Champions trophy in England in June this year.
A delighted Ahmed hailed his bowlers.
"I am very happy because when you give an opportunity to someone and he performs, its great," said Ahmed of the 23-year-old Shinwari, playing only his second game.
"Usman finished the match in the first five overs. We're going from strength to strength, we have lots of options. I want our batting to perform more, if we score 270-280, our bowling is strong to defend that."
Ahmed said his bowlers were at their best throughout the series.
"We did not have (Mohammad) Amir due to injury but Shinwari filled that gap and throughout this series we did well with the ball and this is a great sign for us," said Ahmed.
Pakistan have not allowed any of their opponents to cross 250 mark in the last nine matches, since conceding 319 to India in the Champions trophy group match at Edgbaston in June this year.
Right-arm pacer Hasan Ali has been in great form, taking 12 wickets in this five-match series which also saw him rise to world number one in ODI rankings.
Sri Lankan skipper Tharanga also singled out Pakistan's bowling as the difference.
"Throughout the series we did not have answer to Pakistan's bowling as they were outstanding," said Tharanga whose team was restricted to totals of 209-8, 187, 208, 173 and 103.
"We're not playing to our strengths, to our capability. We didn't score 200 three times. Couldn't handle the pressure, has no answers to Usman's first spell.
"They were straight, always trying to get wickets (Pakistan's bowlers)."
The two teams now play a three-match Twenty20 series, the first two in Abu Dhabi on October 26 and 27 while the last in Lahore on October 29.