He said this recent episode could be an important test, “since it’s the first case to fall under the provisions of the law.”

Romania, which was allied with Nazi Germany from 1940 to 1944, had a prewar Jewish population of about 800,000. Today that number is thought to be fewer than 11,000. A 2004 report by an international commission led by Mr. Wiesel estimated that during the war years, 280,000 to 380,000 Jews died in Romania or in areas under its control.

In a statement on Saturday, the Romanian Ministry of Foreign Affairs expressed its regret over the vandalism at Mr. Wiesel’s childhood home, and condemned “any anti-Semitic gestures and any behavior or expression that promotes intolerance and xenophobia.”

Mr. Wiesel died in 2016 in Manhattan at the age of 87, and spent most of his adult life in the United States. He was born in Sighetu Marmatiei in 1928. At the age of 15, he was deported to Auschwitz, along with his family and other Jews from the area. His mother and youngest sister died in the camp.

Mr. Wiesel, who became an eloquent witness for the six million Jews slaughtered in World War II, wrote several dozen books on the Holocaust, including the memoir “Night,” which remained a best-seller decades after it was first published. He was awarded the Nobel Prize for Peace in 1986.

In a statement published on the website of the Elie Wiesel National Institute for the Study of the Holocaust in Romania, Alexandru Florian, the institute’s director general, described the graffiti as a “grotesque act.”

It “is not just an attack on Elie Wiesel’s memory,” he said, “but on all the victims of the Holocaust.”