PARIS - France, Britain and Germany confirmed on Tuesday that they had triggered the dispute mechanism in the Iran nuclear deal given Tehran's ongoing violations, but said they were not joining the United States campaign to exert maximum pressure on Tehran.

"We do not accept the argument that Iran is entitled to reduce compliance with the JCPoA," the three countries said in a joint statement, saying they had no choice but to trigger the process that could eventually lead to U.N. sanctions.

"Instead of reversing course, Iran has chosen to further reduce compliance."

Iran took a further step back from its commitments to the 2015 pact, with six world powers, by announcing on Jan. 6 that it would scrap limits on enriching uranium, though it said it would continue cooperating with the U.N. nuclear watchdog.

"We do this in good faith with the overarching objective of preserving the JCPoA and in the sincere hope of finding a way forward to resolve the impasse through constructive diplomatic dialogue, while preserving the agreement and remaining within its framework," they said.

In a bid to keep the door open for diplomacy, the three said they were not joining the United States campaign to implement maximum pressure against Iran.

"Given recent events, it is all the more important that we do not add a nuclear proliferation crisis to the current escalation threatening the whole region," they said.

(Reporting by John Irish, Editing by Leigh Thomas) ((john.irish@thomsonreuters.com; 0033-1 49 49 53 42;))