Mr Sarkozy's reassurance comes after rising tensions between Russia and Ukraine over its Crimea region.
Ukraine has also been offered an association agreement with the EU, to be signed next year.
The accord represents cautious support for possible eventual EU membership for Ukraine.
"In the eyes of Europe, [territorial integrity] is absolutely non-negotiable," Mr Sarkozy said in a response to a question from reporters in Paris.
He underlined that the accord left the path for future membership of the 27-member state bloc open, saying: "This association accord does not close any avenues."Click here for full story.
Source BBC On-line