He reported this on Twitter, according to Ukrinform.
"Shocked by the unprecedented attack of the Nova Kakhovka dam. The destruction of civilian infrastructure clearly qualifies as a war crime - and we will hold Russia and its proxies accountable," Michel said.
He noted that he would raise this issue at a meeting of the European Council in June and would propose more assistance to the population of the flooded areas.
"My thoughts with all the families in Ukraine affected by this catastrophe," he added.
Russian troops blew up the dam of the Kakhovka Hydroelectric Power Plant in the early morning hours of Tuesday, June 6.