The Irish developer had recently expressed interest in lease auctions off California and in the Gulf of Maine.
A spokesperson told Windpower Monthly: “Mainstream recently concluded its annual strategic review of the business, part of which involved a comprehensive market review.
“As part of this process, the business made the decision to prioritise its more advanced offshore projects and opportunities across Asia and in European waters in the near term, and as a result, Mainstream has scaled back its focus on the US market.
“However it is important to note that it still remains a market of significant opportunity and ambition for Mainstream.”
The announcement comes as the US offshore wind sector prepares to launch its first commercial-scale projects and to reap tax-breaks, subsidies and other incentives in the climate-boosting Inflation Reduction Act.
Mainstream has a 21.6GW portfolio of onshore and offshore wind and solar PV projects either in development, under-construction or operating in Africa, Asia, Europe and South America, according to the first-quarter investor presentation of its owner Aker Horizons.
The developer made a €556 million net loss in 2022, according to the financial results of its owner, Norwegian investor Aker Horizons. It made a €46 million net loss in the first quarter of 2023, compared with a €53 million net loss one year earlier.