Nicolas Sarkozy has called for urgent action to get the European Union out of its constitutional "paralysis".
He made the call as he met German Chancellor Angela Merkel for talks in Berlin, capping a whirlwind first day as the new president of France.
Germany holds the presidency of the European Union and G8 group of industrialised nations.
Earlier, Mr Sarkozy took office at the Elysee Palace and called for change and national unity in his inaugural speech.
Mr Sarkozy was greeted with full military honours on arrival in Berlin.
At a joint press conference with Mrs Merkel, Mr Sarkozy called the historic relationship between the two nations "sacred" and said they must "get down to work immediately" to resolve the constitutional crisis in the EU.
"The first matter of urgency is to get the European Union out of its current paralysis," Mr Sarkozy said.
Mrs Merkel thanked Mr Sarkozy for visiting Germany on the first day of his presidency and said the meeting was a sign that both sides wanted to intensify the friendship between the two nations.
"I think it is a sign of the great German-French friendship which we can build on, which we want to continue and which is - if you look at the history of the last decades - a miracle, a miracle that has brought together the people of our countries," she said.
The two leaders are expected discuss Mr Sarkozy's plans to relaunch the EU constitution over dinner on Wednesday.
French and Dutch voters rejected the constitutional treaty in 2005, leaving the 27-nation body in limbo, and Mrs Merkel is keen to hammer out a deal to modernise EU structures before next month's summit in Brussels.
Mr Sarkozy has said he wants a simplified treaty to be ratified as quickly as possible by the French parliament.
He also called for more co-operation on industrial issues, particularly over the troubled European aerospace company EADS, which owns aircraft maker Airbus. France and Germany share management of the company.
The BBC's Tristana Moore in Berlin says the two leaders have met many times before and are said to have a good personal relationship.
Earlier in Paris, he said his first decision was to make all schools read a letter home written by a World War II resistance fighter.
Born in France, 1924
Communist fighter during World War II
Detained with other Communists in Chateaubriant
Executed on 22 October 1941 as revenge for the killing by members of the French Resistance of German Feldkommandant Karl Hotz
Wrote a letter to his parents before his execution
He said he could never read Guy Moquet's letter - written before his execution in 1941 - without being "profoundly moved", and said it was essential children knew the horror and barbarism of war.
Mr Sarkozy, 52, defeated Socialist candidate Segolene Royal in the 6 May run-off.
In his inaugural address, he said France needed "to take risks and follow initiatives".
The country also needed to "rehabilitate the values of work, effort, merit and respect" and defeat intolerance, he said.
Mr Sarkozy, formerly interior minister, has a reputation as a law and order hardliner. He made the fight against illegal immigration and crime prominent in his election campaign, along with the issue of national identity.
He won with 53% of the vote and enjoys a powerful mandate after a massive turnout by the electorate.
Mr Sarkozy is not expected to name his prime minister until Thursday. An announcement on his cabinet is expected on Friday morning, government sources told AFP news agency.
A former minister, Francois Fillon, is expected be made prime minister.
Reports also suggest that a senior member of the defeated Socialist party, Bernard Kouchner, is a leading candidate for the post of foreign minister.