Iraq said it had fired a military commander and launched an investigation after admitting the drone attack on its neighbour's East-West pipeline had originated in one of its provinces bordering Iran.
The 1,200km (745 mile) pipeline has helped Saudi Arabia - the world's largest crude oil exporter - bypass the Strait of Hormuz.
The incident comes amid a major advance by the Iranian-backed Houthi rebels in Yemen, putting more pressure on global oil shipping routes as the US-Iran war stretches into its seventh month.
Riyadh on Friday said it had shut the pipeline as a precaution, as satellite images of scorched ground and smoke near the site emerged.
The foreign ministry said the attack resulted in some injuries and damage, which was still being assessed.
