Last financial year the bank lent more than A$75 billion ($77.7b) to homebuyers and A$7.3b to small businesses. "The bigger issue is that not as many people — particularly investors — are applying for loans," he said.
"We see this as a natural response to a recent increase in the supply of housing, along with a fall in foreign investor demand and increased uncertainty about future returns from housing investment after a significant run-up in prices."
Hartzer described it as a "cyclical adjustment after six strong years of growth, that so far regulators and banks are managing reasonably well".
"Having said that, uncertainty about the future direction of regulation and government policy is having an effect on business and consumer confidence," he said.
"As further reforms and legislative changes are enacted, it will be important to avoid changes that unintentionally impact the availability or pricing of credit, or have detrimental effects on the very consumers they are designed to protect."
House prices across the country fell for the 17th consecutive month in February, with Sydney and Melbourne now 13.2 per cent and 9.6 per cent from their respective peaks in July and November 2017.
Economic data released Wednesday showed Australia's growth rate slowing to 2.7 per cent in calendar 2018 and just 0.2 per cent in the December quarter.
While Australia has not had a recession — defined as two consecutive quarters of negative growth — for nearly 30 years, some economists have seized on the figures to claim the country is now in "per capita recession".
When divided by head of population, Australia's GDP growth actually contracted by 0.1 per cent and 0.2 per cent in the September and December quarters.
Some experts say the figures highlight the country's over-reliance on high immigration to artificially boost economic figures while living standards go backwards.