US oil settles down 10 cents, at $60.20 a barrel

Oil prices pushed lowered by Opec

Oil prices closed modestly lower on Monday, retreating from the sharp rally of the previous session, on the impact of a strong dollar and worries of stubbornly high supplies as OPEC prepared to meet this week to stick to production targets.

U.S. crude settled down 10 cents, or 0.2 percent, at $60.20 a barrel, while front-month Brent crude slipped 75 cents to $64.80 a barrel.

The Organization of the Petroleum Exporting Countries pumped at a two-and-a-half year high of 31.22 million barrels of oil per day (bpd) in May, a Reuters monthly survey showed.

The boost from OPEC puts output further above its target of 30 million bpd, underlining the focus of top exporter Saudi Arabia and other key members on market share.

Read MoreOil price: Why further falls may be on the way

The group meets on Friday and is expected to maintain its current production policy, keeping the world oil market amply supplied for the foreseeable future.

"OPEC continues to produce well above target, and also well above demand for its oil," said Carsten Fritsch, senior oil analyst at Commerzbank in Frankfurt.

Gas demand increases as Americans hit the road

Both benchmarks had jumped 5 percent on Friday, their strongest gain in 1½ months, amid a stall in the dollar's rally.

The dollar, which has surged lately on speculation of a U.S. rate hike before the year end, hit session highs on Monday after stronger-than-expected U.S. construction spending and Greek debt woes.

A strong greenback makes dollar-denominated commodities, such as oil, less affordable for holders of other currencies like the euro.

Read MoreUS oil production at 43-year high as OPEC prepares to meet

"The dollar's exerting it's strength and the noise around OPEC is generating into weaker sentiment," said Phil Flynn, analyst at the Price Futures Group in Chicago. "That said, demand for crude and rig cuts on the U.S. side continue to be better than thought."

Improving U.S. demand for crude amid a seasonal peak in the country's road travel mitigated some of the market's downside, said traders. Data from market intelligence firm Genscape showed a draw of more than 1.1 million barrels between Tuesday and Thursday at the Cushing, Oklahoma delivery point for U.S. crude futures, market sources said.

Some noted that the U.S. oil rig count posted new declines last week, against expectations of a rise, which signaled recent price rebounds have not yet prompted drillers to rush into putting new wells into operation.

Goldman Sachs however sounded a bearish note, saying U.S. oil production was on track to grow 155,000 bpd day in the fourth quarter compared with the same period in 2014, despite falling rig counts.