Russian President Vladimir Putin and Iranian President Hassan Rouhani attend a news conference, after a meeting in the Black sea resort of Sochi, Russia, 14 February 2019.

WASHINGTON — Russia's Foreign Ministry slammed U.S. President Donald Trump's decision Wednesday to tighten sanctions on Iran.

The U.S. accused Iran of carrying out strikes Saturday on the world's largest crude-processing plant and oil field in Saudi Arabia. The attacks forced the Saudi kingdom to shut down half of its oil production operations.

Russia, Iran's top ally, called the sanctions "destructive" and added that they "will not solve anything," Reuters reported, citing news agency Interfax.

Trump announced via Twitter on Wednesday that he ordered the Treasury Department to "substantially increase" sanctions on Iran.

It was not immediately clear what steps Trump directed Treasury Secretary Steven Mnuchin to take. The Treasury Department, White House and State Department did not immediately respond to CNBC's requests for comment.

Saturday's pre-dawn strikes on Saudi Arabian oil facilities triggered the largest spike in crude prices in decades and renewed concerns of a budding conflict in the Middle East. All the while, Iran maintains that it was not behind the attacks.

Oil prices have since fallen back as Saudi Arabia said production would return to normal sooner than expected.

On Wednesday, Saudi Arabia's defense ministry said that drone and missile debris recovered by investigators shows Iranian culpability. Saudi coalition spokesman Col. Turki al-Maliki said during a press briefing in Riyadh that all military components retrieved from the oil facilities "point to Iran."