Mr Morrison is misleading the public with political spin, because the deeming rate change was a standard procedure of government.
"For Scott Morrison to claim he's the pensioners' friend is outrageous."
Seniors advocacy body COTA Australia said contrary to claims, it was not a pension increase.
The group is also concerned about longer-term government policies set to decrease the value of the pension over time.
A budget measure languishing in parliament will cut the rate of pension increase from 2017 by targeting the payment it to CPI rather than male weekly earnings - a move that Labor claims will leave pensioners as much as $80 a week worse off within a decade.
"This will result in a serious loss of pension income over time," COTA chief Ian Yates said.