The regulator said today (Friday 30 June) that the deal could potentially mean "less choice for designers", as the two businesses would stop competing with each other.
Sorcha O'Carroll, senior mergers director at the CMA, said: "We're worried this deal could stifle innovation and lead to higher costs for companies that rely on Figma and Adobe's digital tools, as they cease to compete to provide customers with new and better products."
The watchdog has asked Adobe to come up with solutions that can allay its concerns about the deal. If Adobe's response proves unsatisfactory, the CMA will launch a deeper investigation into the deal and could ultimately block it, if such action is deemed necessary.
The proposed deal was originally announced in September last year.
Adobe said: "The combination of Adobe and Figma will deliver significant value to customers by making product design more accessible and efficient, reimagining creative capabilities on the web and creating new categories of creativity and productivity.
"We remain confident in the merits of the case, as Figma's product design is an adjacency to Adobe's core creative products and Adobe has no meaningful plans to compete in the product design space.
"We look forward to establishing these facts in the next phase of the process and successfully completing the transaction."
If the CMA moves against the deal it would not be the first time that it has flexed its muscles against a planned tie-up between two US companies.
In April this year, the CMA took steps to block Microsoft's £56bn ($69bn) acquisition of games giant Activision Blizzard – often referred to as possibly the biggest takeover in tech history – over concerns that it would "alter the future of the fast-growing cloud gaming market", leading to reduced innovation and fewer choices for UK gamers.
The two companies are currently appealing against the CMA's decision and are expected to go to a tribunal next month.
Speaking at the time in response to the CMA's decision, Brad Smith, vice chair and president of Microsoft, said the company was "especially disappointed". A spokeswoman for Activision Blizzard described the UK as being "clearly closed for business".
Matters got worse for the two companies in June, when the Federal Trade Commission (FTC) asked a judge in the US to block the takeover in that territory. The FTC said the deal would "substantially lessen competition" in the video games industry.
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