(Recasts with French source clarifying position)

PARIS, May 7 (Reuters) - European powers will turn to a dispute mechanism that could reimpose international sanctions on Iran if Tehran reneges on parts of the 2015 nuclear deal with world powers, French presidential sources warned on Tuesday.

Iranian state news reports have said Iran does not plan to pull out of the deal, but will revive some nuclear activity that was halted under it. Iran’s president is due to speak on Wednesday.

“We do not want Tehran to announce tomorrow actions that would violate the nuclear agreement, because in this case we Europeans would be obliged to reimpose sanctions as per the terms of the agreement,” a French source said.

France, Germany and Britain, the European signatories to the agreement that lifted sanctions against Tehran in exchange for restrictions on Iran’s atomic activities, have scrambled to save the deal amid U.S. efforts to isolate Tehran since it announced its withdrawal a year ago.

However, the three have repeatedly warned Iran that it must comply with all aspects of the deal and most importantly the elements related to nuclear activity.

Those restrictions have increased the time Iran would need to build a nuclear bomb if it chose to do so. The United States and the U.N. nuclear watchdog believe Iran had a nuclear weapons programme that it abandoned. Iran denies ever having had one.

A second French official later said the suggestion that sanctions would be reimposed if Tehran reneged was referring to a mechanism within the deal itself.

“We don’t want to go as far as sanctions and want Iran to respect its commitments and that’s the message we passed to Tehran and Washington,” the official said.

The deal provides a mechanism for states to complain if the accord is being breached, and ultimately for sanctions to be reimposed unless the U.N. Security Council votes to extend relief.

“Tomorrow, depending on what is in the statement from Tehran, at this stage what we’re expecting is a collective European reaction but as we do not yet know exactly what will be in it, we are preparing for different eventualities,” the first official said. (Additional reporting and writing by John Irish; editing by Richard Lough and Dale Hudson)