During the talks on Tuesday, Merkel received guarantees from PSA chief executive Carlos Tavares that the French company would uphold existing job, investment and site guarantees and maintain Opel as an independent company.
"It is now up to the companies concerned to bring their discussions to conclusion. The chancellor will accompany this process positively," said Steffen Seibert, Merkel's spokesman.
The surprise announcement last week that Peugeot and Citroen maker PSA was eyeing GM's European brands Opel and Vauxhall prompted fears in Germany and Britain that the prospective new owner could cut non-French jobs if the deal goes ahead.
But Opel workers have secured a jobs guarantee from the current management that runs until the end of 2018 and a pledge to continue investing in German sites until 2020, among other deals.
Opel operates some 10 factories in Europe spread across six countries, and had 35,600 employees at the end of 2015 -- 18,250 of them in Germany.
Founded in 1862, Opel, with its lightning-bolt emblem, has long been a familiar sight on German and European roads.
But in recent years the firm has booked repeated losses, costing Detroit-based GM around $15 billion (14 billion euros) since 2000.
A sharp fall in the pound since Britain's vote to quit the EU last June sank Opel's hopes of getting back into the black in 2016, and it ended up reporting a loss of $257 million.
Britain, where it sells vehicles under the Vauxhall brand, is Opel's largest European market.
British Prime Minister Theresa May is due to hold talks with Tavares in the near future to discuss his plans for Vauxhall.