He said production capacity at the targeted plants would be fully restored by the end of the month, in part by drawing from Saudi reserves of crude oil.
The official, who spoke to the media anonymously, added: "The Houthis have never employed this type of Unmanned Aerial Vehicle (UAV) - neither the UAV nor the cruise missiles employed in the attack can reach the facilities from Yemen".
The news conference by Saudi military spokesman Col.
But Tehran has denied any link to the attacks, which at one point disrupted half of Saudi Arabian production.
The officials did not provide evidence or explain what USA intelligence they were using for evaluating the attack that cut 5 percent of global production.
American president Donald Trump has pulled the United States out of the nuclear agreement, but Britain has remained in the pact.
Saudi's de facto leader Crown Prince Mohammed bin Salman told Russian leader Vladimir Putin in a phone call the kingdom wants an worldwide investigation that would be seen as highly credible, the state news agency SPA reported.
However, he added: "We're trying not to react too quickly because the last thing we need is more conflict in the region".
The Islamic Republic dismissed the allegations.
"They want to impose maximum. pressure on Iran through slander", Iran's President Hassan Rouhani said.
The new stage of the long-running US-Iranian standoff has raised speculation over whether it will lead to conflict.
Iran threatened it would retaliate against any action "immediately", with state-run news agency IRNA saying: "If any action takes place against Iran, the action will be faced by Iran's answer immediately".
On Wednesday, Rouhani defended Yemen's right to respond to Saudi attacks on the country and said Saturday's attack should be considered a "warning" by Yemen's Houthi rebels.
Secretary of State Mike Pompeo was expected to arrive in Saudi Arabia today to speak with Crown Prince Mohammed bin Salman about counter measures against Iran. He said Saudi Arabia was working to share the information with United Nations experts. Secretary-General Antonio Guterres warned that a major confrontation in the Gulf would have "devastating consequences" for the region and globally.
The U.S. has already imposed sweeping sanctions on much of Iran's economy - especially its oil sales - since exiting the landmark 2015 nuclear deal past year in an effort to curtail Tehran's regional influence and military capabilities.
A U.S. official told Reuters the strikes originated in southwest Iran. A Saudi official also said plans for the listing of the country's oil giant, Aramco, would continue "as is".
The "evidence" the Trump administration produces to implicate the culprit should be examined with a critical eye, given that these tensions began in May with the deployment of a massive military force towards the Gulf to threaten Iran.
Russian President Vladimir Putin also discussed the weekend attacks by phone with Salman on Wednesday, the Kremlin said.
Iran is the regional rival of Saudi Arabia and an opponent of the United States, which pulled out of a treaty aimed at limiting Tehran's nuclear programme after Mr Trump took power.