INTERNATIONAL NEWS - His trip comes days after Lebanese PM Saad Hariri resigned while in Riyadh, saying he feared for his life.
Foes Saudi Arabia and Iran have accused each other of fuelling instability in Lebanon and the wider region.
Mr Macron and Saudi officials also discussed the crisis in Yemen, where Riyadh is leading a war against rebels.
France has historical ties with Lebanon, as its former colonial power before it gained independence during World War Two.
The French president was in the United Arab Emirates on Thursday to open the Louvre Abu Dhabi, a spin-off of the famous Paris art museum.
Speaking there, he announced his unexpected two-hour trip to Riyadh to hold face-to-face talks with Saudi Crown Prince Mohammed bin Salman, and "emphasise the importance of Lebanese stability and integrity".
