The report revealed that overall prices increased 3.1 per cent in May from a year earlier, the largest annual increase since 2012.
Prices excluding food and energy rose by 2.4 per cent and prices excluding food, energy and trade services climbed 2.6 per cent.
The higher than expected index hike emerged ahead of the summer driving season where motorists are also likely to be stung at the pumps.
"Oil prices are too high, Opec is at it again. Not good!", Trump told his 53 million Twitter followers.
The outburst follows a warning from the President earlier this year that "artificially very high" oil prices would not be accepted.
Trump said, via Twitter: "Looks like Opec is at it again. With record amounts of oil all over the place, including the fully loaded ships at sea, oil prices are artificially Very High! No good and will not be accepted!"
The latest warning comes days before a key make or break meeting of Opec and its allies.
Opec and non-Opec producers, led by Russia, will meet in Vienna late next week to decide whether the 17-month long pact to cut 1.72 million barrels of oil production a day should remain.