International Benchmark Brent crude traded at $75.57 per barrel at 09.42 GMT+2 while American benchmark West Texas Intermediate (WTI) saw prices of $70.45 per barrel on Monday.
On Friday afternoon, Brent oil traded at $73.87 per barrel at 15.13 GMT+2 while WTI saw prices of $68.69 per barrel.
Brent reached over $75 per barrel last Monday over uncertainty on whether the U.S. would pull out of the Iranian nuclear deal.
Under a deal signed in 2015, the U.S. and other world powers agreed to lift some of the economic sanctions imposed against Iran in return for the latter agreeing to rein in its nuclear program.
U.S. President Donald Trump has repeatedly called the pact "one of the worst negotiated agreements" he has ever seen. He has threatened to pull the U.S. out of the deal and has to make a decision on whether he will do so by the May 12 deadline.
In addition, according to Iran's Shana News Agency, Iran's Minister of Petroleum, Bijan Namdar Zangeneh said that Tehran prefers "reasonable" oil prices to help crude prices avoid market instability.
He explained that "reasonable crude prices" would likely encourage producers to keep supplies in the market while preventing global markets from plunging into instability.
- Oil rigs to rise in the U.S.
In the meanwhile, the number of oil rigs in the U.S. increased by nine this week with the likelihood of ramping up production, according to oilfield services company Baker Hughes data released on Friday, counteracting the rising oil price trend.
The oil rig count in the country rose to 834 for the week ending May 4, from 825 in the previous week, the data showed.
This marked the 13th weekly increase in the number of oil rigs in the past 15 weeks.
By Gulsen Cagatay