"I told you @TIME Magazine would never pick me as person of the year despite being the big favorite. They picked person who is ruining Germany," he tweeted.
Last month, Trump slammed Merkel, the German chancellor, for allowing a wave of Syrian refugees into Germany, saying she should "be ashamed of herself." Trump said he had respected her but added, "She blew it, when she allowed this to happen, this migration."
Trump first predicted that TIME would not name him Person of the Year at a Birmingham, Alabama, rally last month.
In announcing the choice, TIME Managing Editor Nancy Gibbs praised Merkel's handling of multiple economic and national security issues.
"She has stepped up in a way that was uncharacteristic even for her," Gibbs said on NBC's "Today." "She's been a very long-serving leader, the longest-serving in the West. She controls the world's fourth-largest economy, but this year she really was tested in how she would respond to some of the most difficult challenges that any leader is facing in the world."
Trump was a finalist along with Black Lives Matter activists, ISIS leader Abu Bakr al-Baghdadi, Russian President Vladimir Putin, Iranian President Hassan Rouhani, transgender reality star Caitlyn Jenner and Uber CEO Travis Kalanick.
In addition to the magazine's story on Trump, Time also appeared to tweak the candidate after he dinged the magazine.
The publication published a second story
with a one-minute video behind the scenes of a photo shoot in the mogul's office from August. The video featured several blooper reel moments with Trump's co-star of the shoot, a bald eagle named Uncle Sam.
Time tweeted out the story with a gif of the eagle flapping his wings at Trump, who quickly ducked out of the way.