Barroso's appointment as non-executive chairman and general adviser to Goldman Sachs International, which is based in London, is widely seen as an attempt to limit the negative effects of the U.K.'s decision in late June to leave the EU on the bank.
But the organizers of the petition, who call themselves a "group of employees of the European Institutions," said that by taking up banking role, Barroso was guilty of "irresponsible revolving-door practices" of former EU officials joining the private sector.
The group claimed the EU's reputation would suffer further at a time when public opinion towards the body was already low.
"(We) have come together because we are more and more concerned by the European project's deteriorating image among our families, friends and neighbours as well as the many citizens we encounter all over Europe," the petition's creators said.
"This decision to go and work for one of the banks most implicated in the subprime crisis that led to the financial crisis of 2007-2008… as well as one of the banks most involved in the Greek debt crisis…is a further example of the irresponsible revolving-door practices, which are highly damaging to the EU institutions and, even if not illegal, morally reprehensible."
The petition argued that Barroso's appointment was "irresponsible" because it "feeds into a political context which is not only euroskeptic but now even openly europhobic" and that "It is morally reprehensible, in that it runs counter to the honour and probity of a European civil service supposed to defend the general European interest."
The petition called for the suspension of Barroso's pension allowance from the Commission "for the period of his employment at Goldman Sachs and beyond" and "the suspension of all possible honorary titles linked to the European Institutions."
It also called for more rules to "fight such revolving-door practices that apply to former Members of the Commission, in proportion to the damage that their future behaviour can bring to the European civil service and the European Union."
The European Commission would not comment on the appointment but Goldman Sachs said Barroso had complied with an 18-month working restriction period after leaving his EU role in 2014, the Financial Times reported.
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