Steve Smith then anchored the Australian run chase as he and Ben McDermott added 58 runs for the third wicket stand before McDermott was trapped in front of the wicket of Imad Wasim.
This is the 2nd T20I of the three-match series.
Pakistan, who are now the top-ranked T20I side have not had a good time in the game's shortest format so far.
The decision to rest Cummins may well open the way for Sean Abbott to play his first global in more than five years, as Australia look for a victory at Perth Stadium on Friday evening to close out an unbeaten six matches against Sri Lanka and Pakistan, where so far only Sydney rain and arcane playing conditions have prevented a clean sweep.
UMPIRES: G.A. Abood (Australia) and S.A.J.
"We've got so much cricket on, he [Cummins] plays a lot of it so when you get a little opportunity rather than taking the long flight to Perth he's going to stay here, recover and get prepared for the Test series", Australia coach Justin Langer said.
He and Starc both claimed two wickets in Sunday's win over Pakistan, and arrive in Canberra full of confidence for the second game of the series against the tourists.More news: Jim Jordan: Republicans Want to Subpoena Whistleblower to Testify in Public Hearing
More news: White House beefing up team to fight impeachment inquiry PR battle
More news: CCB arrests two batsmen in KPL spot-fixing scandal
Across nine matches in 2015-16, Smith returned 263 runs at 32.87 and a strike rate of 135.56, before bowing out of T20I duty to provide brief periods of rest between his many Test match and ODI commitments.
Former captain Smith took 15 off the 17th over from Amir and struck 11 boundaries before watching on from the other end as Ashton Turner struck the winning run in the penultimate over.
"I don't doubt my ability". He took the game away with magnificent innings.
"I think that's based off ground size, how true the wickets are too". The white ball usually flies off the bat particularly when it's brand new. "If you're timing the ball well, you get value for your shots normally".
Pat Cummins has been on active duty for Australia across the formats all year. "Everyone is playing their roles really well, and we've got guys like Steve, who does what he does best".
The groom's message read: "As a die-hard cricket fan, I want to submit a photo from my wedding this past weekend".