"The court's decision could hardly have been more thorough, fact-based, and well-reasoned", AT&T General Counsel David McAtee said in a statement responding to the Justice Department's move.
In 2001, H.J. Heinz Co called off its acquisition of Beech-Nut after an appeals court overturned a lower court's decision to allow the merger.
It has only been a month since a USA court gave AT&T approval to buy Time Warner.
Critics of the deal have argued the court approval offers an effective green light to other major deals that could end up boosting prices and hurting consumers.
Using unusually strong language, Leon discouraged the Justice Department from asking him to put the ruling on hold while it considers an appeal.
Spokespeople for the DOJ declined to comment. AT&T is a phone, cable and satellite behemoth that became the biggest pay-TV provider in the US with its acquisition of DirecTV in 2014.
Mr Trump has publicly feuded with Time Warner's CNN, calling it "failing" and a purveyor of "fake news". AT&T completed its acquisition of Time Warner on June 14 and formed WarnerMedia a day later.
AT&T argued, during the trial, that it needed to grow to survive in the era of Google, Amazon and Netflix.
It has committed to certain conditions under which it will run Time Warner's Turner Broadcasting, which includes CNN.
In addition, AT&T Communications will have no say in setting Turner's prices or other terms in contracts with companies that distribute its content.
Stay tuned at Heroic Hollywood for more updates on the merger between AT&T and Time Warner.
Trump had previously denounced the AT&T deal, vowing that his administration would block it because it would concentrate corporate power unacceptably.
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