Merkel was speaking a day after starting her third term as leader of Europe's biggest economy and just ahead of a visit to Paris, followed by a two-day EU summit in Brussels.
Arriving for talks with French President Francois Hollande, Merkel hailed what she called a "new phase" in Franco-German relations.
"Together, we want to push Europe forward and make it a strong continent in the world," she said.
For his part, Hollande stressed the "Europe needs France and Germany to have a confident, strong and open relationship".
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"Since the Lisbon Treaty we have a situation in Europe where everyone says, 'we can develop everything but we can't change the treaties'," Merkel said.
"I don't think that we can build a truly functioning Europe that way."
Hollande has rejected changing EU treaties, pushing for more pro-growth policies and less austerity within the existing European charters.
Other EU members are also sceptical about renegotiating treaties, which may require referendums, amid rising euroscepticism in many countries.
"We are among those who say that we must, if treaties are no longer sufficient, develop those treaties."
"Those who want more Europe must be ready for new rules on some competencies," she added.