Merlin, which manages a portfolio of offices and commercial real estate across Spain and Portugal, declined to comment on the report.
At 0914 GMT its shares were trading 11% up at 7.69 euros a share.
Brookfield also declined to comment.
According to Expansion, Brookfield had been interested in acquiring Merlin before the COVID-19 pandemic and has stepped up its plans since the real estate group's market valuation has plunged.
Banco Sabadell said in an analyst note that it sees "significant potential" in the company, which has been trading at a 55% discount to its June net asset value.
But the bank said it remained cautious on the possibility of any deal and that potential suitors might struggle to win over Merlin's shareholders.
Banco Santander owns about 22% stake of Merlin while BlackRock owns 3.1%, Refinitiv data shows.
(Reporting by Nathan Allen and Joanna Jonczyk-Gwizdala; editing by Louise Heavens, Barbara Lewis and David Goodman)