Babar Azam (90) and Hussain Talat's (55) knocks went in vain as Pakistan collapsed from 147-1 to 181-7 courtesy Phehlukwayo and Morris' bowling
South Africa prevailed by six runs in a tense finish after being sent in and making 192 for six.
De Kock slammed 83 off 58 balls as South Africa chased down a target of 241 with seven wickets and ten overs to spare to seal a 3-2 series win.
"Whatever happened has happened," Sarfraz told media at the airport after landing from Cape Town.
This is also the first time ever Pakistan won an ODI against South Africa at the Wanderers
Shoaib Malik will lead Pakistan in the remaining two ODIs and the subsequent T20I series against South Africa
The Pakistan captain later apologised for the comment on Twitter.
Pakistan will play a three-match T20 series against South Africa after the completion of undergoing five-match ODI series
Imam's 101 spurred Pakistan to an imposing 317 for six but South Africa won by 13 runs according to the Duckworth/Lewis/Stern method
Wahab Riaz, Faheem Ashraf included in 20-man shortlist for England Tests
'We maintained a reasonable run rate considering the conditions' - Shan Masood
Shan Masood's a bit annoying to bowl at, says Jofra Archer
The flair, the calmness and the promises: Pakistan's rhetoric in the lead up to first Test
Broad takes 500 Test wickets, Woakes bags five as England reclaim Wisden Trophy
Babar Azam fluency tames sloppy England on rain-curtailed opening day
'Plans underway to stage remaining PSL matches this year' - PCB
Sohail Khan bags five wickets as Pakistan's leading batsmen flounder
Pakistan grapple with selection predicament as fired up England eye strong start
Team Green put on improved batting display after Naseem Shah shines again