European stocks finished lower Friday, but the regional benchmark still nabbed its best monthly gain in more than six years. The U.K.’s FTSE 100 UKX, -0.33% dropped 0.5% to finish at 6,361.09. But Germany’s DAX 30 DAX, +0.90% closed up 0.5% at 10,850.14, and France’s CAC 40 PX1, +0.46% ended higher by 0.2% at 4,897.66. Some of this month’s gains came last week, after European Central Bank President Mario Draghi signaled the bank is open to ramping up its stimulus efforts in December.