"Macron ... what can you say? Had enough of him, there you are!" Aubry told journalists at a press conference that was supposed to be about her plans for Lille, the city where she is mayor, and December's regional elections.
She went on to accuse the minister of arrogance and ignorance of people's everyday lives and took a swipe at Prime Minister Manuel Valls, who appointed Macron, for not putting into practise a party resolution calling for more redistribution of wealth.
Macron, who is not a Socialist Party member and has been a civil servant and a merchant banker, has spoken out against a number of policies that are dear to the hearts of the left.
His latest sally was against civil servants having jobs for life, a measure Aubry declared guards against corruption and guarantees a strong state.
Macron has also criticised French labour law and the 35-hour working week, introduced by Aubry when she was labour minister in the 1990s.
Twelve areas of Paris were designated by decree on Thursday as zones where shops targeting tourists could open on 12 Sundays per year.
That has caused a clash with Paris Mayor Anne Hidalgo, who initially opposed the change and later accused the minister of imposing the zones without sufficient local knowledge.
Left-wing Socialist activist Gérard Filoche went a step further on Wednesday.
Asked about Aubry's comments, President François Hollande said he did not want to comment "but sometimes silence is golden".