Morrisons private equity buyers have agreed to sell a number of petrol stations to accelerate the £7 billion takeover.
Clayton, Dubilier and Rice, which also owns forecourt operator Motor Fuel Group (MFG), won over control of the Big Four grocer in October.
However, the Competition and Markets Authority launched an investigation because MFG owns 921 petrol stations while Morrisons has 339.
The regulator found that the takeover could increase prices in 121 locations across the UK where they both operate.
It said the findings were particularly important with petrol prices near record highs and gave CD&R a week to propose a way to address its concerns.
The watchdog said CD&R has offered to sell some of its petrol stations to force through the deal.
CD&R won an auction for Morrisons in October after a lengthy battle in which it tipped US private equity rival Fortress by 1p per share.
MFG is the UK’s biggest independent forecourt operator with petrol stations across brands such as Texaco, BP and Shell.
CD&R did not say how many forecourts it has offered to sell, but the CMA said the deal “might be accepted” under the proposals.