In Monday’s interview, Mr. Almunia said Google needed to offer the commission a solution where choices between Google-branded search results and those of its competitors were clearly visible within the search engine both on desktop computers and on mobile devices.

“I don’t know if you should call it labeling, or whatever, but they need to distinguish,” Mr. Almunia said.

“In some cases this can be achieved through the information you will receive through the natural search results,” he said. “In other cases, maybe we will ask Google to signal what are the relevant options, alternative options, in the way they present the results.”

The choice “should be a real one,” he said.

Mr. Almunia said regulators were not requiring Google to make changes to its algorithm, the secret formula that the company uses to determine the best responses to search queries.

In terms of the way Google uses and displays snippets of information from other Web sites in its search results, he said he expected Google to accept that other companies could choose “to allow or not to allow Google to use the content, but this decision cannot have as a consequence the punishment of those who will not allow the use of the content in terms of search results.”

Web sites and some publications have complained in recent years of virtually disappearing from Google’s search engine if they posed a competitive threat or did not comply with Google’s terms.

Mr. Almunia said he would test any changes that Google proposed to make by sending questionnaires to competitors, including the complainants, and to other companies.