"We are committed to continuing to work cooperatively with regulators around the globe to allow the transaction to proceed, but won't hesitate to fight to defend the transaction if required," an Activision Blizzard spokesperson said.
Microsoft, maker of the Xbox game console, announced in January the deal to buy Activision, the maker of "Call of Duty" and "Candy Crush" games, in the biggest gaming industry deal in history as global technology giants staked their claims to a virtual future.
The acquisition could damage the industry if Microsoft refused to give rivals access to Activision's best-selling games, Britain's antitrust regulator has said.
The deal has drawn criticism from Sony, maker of the Playstation console, citing Microsoft's control of games like "Call of Duty.".
"Sony, as the industry leader, says it is worried about 'Call of Duty,' but we've said we are committed to making the same game available on the same day on both Xbox and PlayStation," Microsoft President and Vice Chair Brad Smith has said.
A spokesperson for Microsoft said: "We are prepared to address the concerns of regulators, including the FTC, and Sony to ensure the deal closes with confidence.
We’ll still trail Sony and Tencent in the market after the deal closes, and together Activision and Xbox will benefit gamers and developers and make the industry more competitive.".