Amazon.com Inc.’s $1.4 billion deal for Roomba maker iRobot Corp. risks being derailed unless the firms fix a list of competition concerns highlighted by the European Union’s antitrust arm.

The European Commission in Brussels issued a so-called statement of objections on Monday, warning how Amazon’s proposed deal could hurt the robot vacuum cleaner market and let the e-commerce giant strengthen its position in online marketplaces and in other data-related services.