"I'm contracted to September 2019 and that will see me out," he told the BBC.
England finished at 180 for nine off 88.1 overs as Australia won by an innings and 123 runs.
All four of Australia's front-line bowlers finished with 20 or more wickets each for the series.
Usman Khawaja plundered a big century as Australia roasted England's bowlers on Saturday to open up a 133-run lead with two days to play
At the close, Smith was on 44 with Khawaja reaching his highest score of the series on 91 in Australia's 193 for two
Skipper Root again missed out on an elusive first century in the series as Aussies struck late on the opening day of last Test
Root and Malan stole the highlights on the opening day of the SCG Test
Woakes has taken 10 wickets at 49.5 in the four Tests and scored just 114 runs through seven innings batting number eight at an average of 16.28.
Left-armer Starc is the leading wicket-taker in the series with 19 despite only playing three Tests
Wahab Riaz, Faheem Ashraf included in 20-man shortlist for England Tests
Shan Masood's a bit annoying to bowl at, says Jofra Archer
'We maintained a reasonable run rate considering the conditions' - Shan Masood
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
Pakistan grapple with selection predicament as fired up England eye strong start
England roar back into the contest after 14 wickets tumble on day three
Team Green put on improved batting display after Naseem Shah shines again