WASHINGTON — President Obama declined on Friday to refer to the 1915 massacre of Armenians as genocide, breaking a campaign promise as his presidency nears its end.

Mr. Obama, in a statement to mark Armenian Remembrance Day on April 24, called the massacre the first mass atrocity of the 20th century and a tragedy that must not be repeated. Yet he stopped short of using the word genocide, a term he applied to the killings before he became president in 2009.

“I have consistently stated my own view of what occurred in 1915, and my view has not changed,” Mr. Obama said.

Armenian-American leaders have urged Mr. Obama each year to keep a pledge he made as a presidential candidate in 2008, when he said the United States government had a responsibility to recognize the attacks as genocide and vowed to do so if elected. Mr. Obama’s failure to fulfill that pledge in his final annual statement on the massacre infuriated advocates and lawmakers who accused the president of outsourcing America’s moral voice to Turkey, which staunchly opposes the genocide label.