After losing the first round of the presidential election, he needs to win over far-right voters for the second.
Socialist rival Francois Hollande has argued that some National Front supporters belong on the left.
On Wednesday, he said he respected the wishes of centrist candidate Francois Bayrou, who has yet to declare whom he will back in the second round.
Mr Bayrou won 9.1% of the vote on Sunday, coming fifth, just behind the far left’s Jean-Luc Melenchon on 11.1%.
The shock of election night for many was the 18.1% won by National Front candidate Marine Le Pen, putting her third behind Mr Sarkozy on 27.1% and Mr Hollande on 28.6%.
‘No ministers’
“We need to speak to the 18% who voted for Marine Le Pen,” Mr Sarkozy said.
“I don’t regard this 18% as people with extreme-right ideas… but I don’t want ministers from the National Front. I’ve never wanted that.”
Francois Hollande attends the Armenian ceremony in Paris, 24 April Francois Hollande also attended the Armenian commemoration in Paris
Ms Le Pen is not expected to make her position clear until next week when she addresses a National Front rally on 1 May.
Asked about the far left’s Mr Melenchon, who said this month that he liked Mr Sarkozy’s wife Carla Bruni as a singer, the French president joked that he could say “nothing bad about someone who likes Carla’s songs”.
Mr Sarkozy is due to hold an election meeting in Cernay, in the eastern region of Alsace, on Wednesday afternoon, along with Prime Minister Francois Fillon.
Both Mr Sarkozy and his Socialist opponent attended a ceremony in Paris on Tuesday to mark the 97th anniversary of the mass killing of Armenians by Ottoman Turks.
Mr Hollande is planning to hold a news conference on Wednesday afternoon at the International Union of Railways in Paris.
Speaking to France 2 TV, Mr Hollande said he would respect whatever centrist candidate Francois Bayrou would “say or do” for the second round, and that he did not want to put pressure on him.
Earlier, he argued that part of the Le Pen electorate came from the left and “should be on the side of progress, equality, change, shared effort and justice”.
“It is up to me to convince them that the left defends them,” Mr Hollande said.
A new Le Pen
It has been announced that a niece of Ms Le Pen, Marion Le Pen, will stand for parliament in June in a constituency held by Mr Sarkozy’s UMP party and its predecessors for more than a quarter of a century.
Marion Le Pen, a 21-year-old law student and grand-daughter of Jean-Marie Le Pen, is to stand in the Carpentras constituency in Vaucluse, south-eastern France.
She will be the principal opponent of sitting MP Jean-Michel Ferrand, who has been re-elected there since 1986.
According to regional newspaper La Provence, Marine Le Pen took 31.5% of the vote in the constituency at the presidential election to 27.65% for Mr Sarkozy and 19.1% for Mr Hollande.
Carpentras was gripped by a political row in 1990 when a Jewish cemetery was vandalised and the National Front was accused indirectly. Neo-Nazis later convicted of the desecration had no proven links to the party.
The National Front currently has no MPs in France’s National Assembly.
EU President Herman Van Rompuy has warned of “winds of populism” blowing across Europe.
“Nationalist and extremist movements are on the rise,” he wrote on Twitter during a visit to Romania.
“Many of them blame ‘Brussels’ for bad news. There can only be one response. Telling the truth.”