Petrol retailers say there is a good chance prices will rise next week.
Z Energy, which supplies about a third of New Zealand's petrol, says there has been strong upward pressure on fuel prices since the New Year.
A potential ban by the European Union on oil imports from Iran and possible disruptions to shipping through the Strait of Hormuz have raised its costs by about 7 cents per litre.
If there is no change in the international situation in the next couple of days, Z Energy says prices at the pump may rise next week.
However, Z Energy, BP and Caltex say they will not pass on the extra 7 cents during the weekend, when many people will be returning from their summer holidays.
Mobil could not be reached for comment.
Main centre retail prices are $2.06.9 per litre for 91 octane petrol, $2.14.9 per litre for 95 octane and $1.57.9 - $1.58.9 per litre for diesel.