* Fabius calls for firmness over Crimea but caution
* No new date for routine security consultation meeting
* 1.2 billion euro helicopter contract would be suspended (Adds French foreign minister quotes, background)
MOSCOW/PARIS, March 17 (Reuters) - France has postponed a visit to Moscow by its defence and foreign ministers that had been planned for Tuesday as part of an effort to pressure Russia to de-escalate the crisis in Ukraine.
A Russian Foreign Ministry source told Reuters on Monday about the delayed meeting shortly after President Vladimir Putin signed a decree recognising the Ukrainian region of Crimea as a sovereign state. Crimea declared itself independent and applied to join Russia following a referendum held over the weekend.
A French official confirmed the cancellation of the meeting, which was a regular fixture to discuss security issues between Russia and France, and said no new date had been proposed.
The European Union took a cautious approach to imposing sanctions against Moscow on Monday, targeting 21 people in Russia and Crimea while leaving open the possibility of adding harsher economic measures when EU leaders meet later this week.
The United States took similar steps but appeared to target more senior officials in Russia, including two aides to Russian President Vladimir Putin.
Calling the crisis the gravest since the end of the Cold War, French Foreign Minister Laurence Fabius urged calm to prevent the situation from deteriorating.
"We want firmness to prevail and for Putin to not go any further, but at the same time we want to de-escalate the situation via dialogue," said Fabius in an interview with France 2 television on Monday.
He echoed comments made by French President Francois Hollande on Saturday saying Paris would review military cooperation with Russia as part of a third level of sanctions if Moscow did not react to the initial measures.
Fabius said a 1.2 billion euro helicopter carrier contract signed with Russia in 2011 could be suspended and pointed out that ally Britain was also considering freezing assets of Russian oligarchs in London.
If Russia expanded its incursion to Crimean into nearby eastern Ukraine, then a response would be necessary, he said.
"After a certain point, there will be a reaction, including with force," said Fabius. "Ukraine has already mobilised some people and we cannot allow Russia to do simply anything." (Reporting by Gabriela Baczynska and Leila Abboud; Writing by Alissa de Carbonnel; Editing by Tom Heneghan)