"I think he's starting to feel the breath of history," Juncker told the Italian newspaper La Repubblica on Wednesday.
When asked if he trusted Trump or feared for the president's actions, Juncker said that he viewed Trump with "growing benevolence."
The head of the European Commission has been one of the most critical voices against Trump fro inside Brussels. Juncker has criticized Trump's support for Brexit and his encouraging words for other countries to follow the U.K.'s decision to leave the EU.
"Do not say that, do not invite others to leave, because if the European Union collapses, you will have a new war in the western Balkans," Juncker told U.S. Vice President Mike Pence when he visited Brussels earlier this year.
More recently, Juncker has said that he would promote Ohio's independence if Trump kept encouraging other countries to leave the EU. The former prime minister of Luxembourg has also criticized Trump's protectionist views on trade, stating that a trade war between Europe and the U.S. would not benefit any of the sides.
However, the somewhat softer view on the U.S. president comes a few days after Trump decided to launch a military strike on a Syrian government airbase, following an alleged chemical attack conducted by the ruling regime of Bashar Assad.
According to Aarti Shankar, policy analyst at Open Europe, this increases the possibilities of a strong U.S.- European cooperation on defense and security, "despite Europe's wariness of the Trump administration."
"However, I would not suggest there is a dramatic shift in Europe's perspective of the U.S. president," she told CNBC via email, adding that "the strikes supported Europe's image of President Trump as an unpredictable leader."
Karel Lannoo, chief executive officer at the Brussels-based CEPS think tank, agreed that Europe is viewing Trump in a different way, but it has to find a way to work with the Trump's unpredictability.
"He will continue to be unpredictable, but possibly a bit less than foreseen," he said. "In addition, (Trump) has shown to be good were (Barack) Obama and Europe were weak, to decide, and to show what are limits."