Brent crude fell 0.57% to $115.15 a barrel, while WTI slipped 0.43% to $101.32
Iranian state media reported that the four countries agreed to continue discussions on peace and security.
Riyadh said the visit aimed to establish open channels for negotiations to prevent a renewed military escalation. October has emerged as the worst month for attacks on commercial shipping in the Strait of Hormuz and surrounding waterways, according to data compiled by a Washington-based think tank tracking maritime security incidents. Diplomatic efforts offered some relief to markets, with Saudi Arabia, Turkey and Pakistan holding talks with Iranian officials in Tehran on Monday to ease regional tensions.
Separately, Russian refiners are increasing diesel production in October after the government granted export quotas following a supply agreement between Moscow and Washington, two industry sources, quoted by Reuters, familiar with the matter said.