UNITED NATIONS, Sept 20 (Reuters) - U.S. Secretary of State Rex Tillerson and Iranian Foreign Minister Javad Zarif spoke directly during talks at the United Nations on Wednesday in what a European diplomat described as a "very difficult" meeting.

"Tillerson and Zarif spoke directly for a relatively long time. There was no real great surprise in the positions expressed," the diplomat said.

The diplomat said there was unanimity that the nuclear deal was being respected, but the debate had not really focused on its implementation.

"There was no real visibility on what the American decision will be in October," the diplomat said. (Reporting by John Irish; Editing by Sandra Maler)