Google's job-search tool is being investigated by the EU over claims that it is driving competitors out of the market.
EU competition commissioner Margrethe Vestager questioned whether it was fair the tech giant had "such control over the success or failure" of its rivals.
Google places a widget at the top of searches, circumventing the need to click through to job sites.
Twenty-three job-search sites urged Brussels to take action last month.
While Google does not charge a fee for its facility, its competitors fear the move is a ploy to gain market share before monetising its business model.
Ms Vestager has taken a tough stance against Google in the past, issuing fines totalling 8.47bn euros ($9.40bn; £7.64bn) in similar anti-trust cases.
"We're looking right now at whether the same thing may have happened with other parts of Google's business - like the job search business known as Google for Jobs," she told a conference in Berlin on Tuesday.
Google claimed it had made changes to the tool following feedback in Europe.
It said the alterations included offering direct links to third-party job sites and linking directly to job offers available on a single site.
Earlier this month, the company announced it would prompt European users of its Android operating system to choose their own default search engine from 2020 following criticism from the European Commission.
Google was hit with a record 4.34bn-euro antitrust fine, which it is challenging.