BEIJING–China’s leaders who just a year ago vowed to tackle chronic economic ills set “stability” as their main goal for next year, pledging to contain asset bubbles and financial risks.

At a closed-door Communist Party conclave that ended Friday, senior party officials led by President Xi Jinping hammered out an economic blueprint for 2017 that emphasizes preventing troubles in the country’s housing market and the increasingly convoluted financial system from spinning out of control.

The...