STRASBOURG - A decision by Britain, France and Germany to trigger a dispute mechanism in the 2015 arms control agreement with Iran is not designed to re-impose U.N. sanctions but to bring Tehran back into compliance, the EU's top diplomat said.

Josep Borrell, who is also the chairman of the Iran nuclear deal that the EU helped to broker, told reporters he had received notification from London, Paris and Berlin of their decision to trigger the dispute resolution mechanism.

Its aim "is to resolve issues relating to the implementation of the Iran nuclear agreement (and not)... to re-impose sanctions," Borrell said at the European Parliament in Strasbourg.

(Reporting by Marine Strauss; editing by John Stonestreet) ((robin.emmott@thomsonreuters.com; +32 2 287 6835; Reuters Messaging: robin.emmott.thomsonreuters.com@reuters.net))