In a rare moment of humility, Mr Juncker reminded EU ambassadors Europe was the smallest of the continents and had to be humble.
He told them: “Europe is very small. It is the smallest of the continents.
“While we still believe that we are the masters of the world – we think we are the driving force of international politics — that is not true.
“So we need more modesty.”
Mr Juncker used his speech to the ambassadors, also known as Heads of Delegation, as a warm-up to his much-anticipated State of the Union address to the European Parliament in Strasbourg in two weeks.
At the same time as calling for modesty he also complained that Europeans are often too negative about themselves and the EU.
And Mr Juncker also warned against the rising tide of populism across EU.
He said: “If one follows the populists, one becomes populist.”
And the president also called for improved links with Vladimir Putin and the Kremlin.
He told the ambassadors: “I think we should think about better relations with Russia.
“It depends on Russia, it depends on us, but there won’t be any European security for centuries to come without Russia.”
Mr Juncker’s State of the Union address on September 13 is expected to focus on trade – placing the bloc in direct competition with post-Brexit Britain.
Senior EU officials told EurActiv the EU Commission chief will ask member states for a mandate to start a clutch of new talks with partners across the globe as one of his key missions for 2018.
Mr Juncker is also expected to advocate some form of screening process for foreign investment in European companies to help assuage some free trade sceptics who feel globalisation has gone too far.
In recent months even free market backing Germany has started to raise concerns about Chinese backed takeovers of big companies, including technology giants.