WASHINGTON — A federal judge on Tuesday doubled down on his hesitation to approve the merger settlement between CVS Health and Aetna, asking the combined companies to take steps to keep some operations distinct while he completes his review.

Judge Richard J. Leon, of the United States District Court in the District of Columbia, stopped short of an attempt to block the $69 billion merger, but he reiterated his concerns over the Justice Department’s approval of the combination. He went on to scold the government’s lawyers for being “hostile to the role of the federal courts” in looking after the public’s interest, telling them they “would do well to re-evaluate the tone with which you address this court.”

Judge Leon proposed assigning a government monitor to ensure the two companies remain separate, and he urged them to take steps to “preserve the ability to unwind CVS’ acquisition of Aetna in the event an unwinding is necessary.”

CVS Health, one of the nation’s largest pharmacy benefit managers, has pitched its acquisition of Aetna, the giant health insurance company, as a way to offer patients better coordinated and more efficient care. But consumer groups and others have criticized the deal, saying it would create a powerful entity that would stifle competition and harm consumers.