It follows a rise of the same size in February.
The move was tipped by the majority of economists and money markets, which had priced in the chance of a rise at about two-thirds before the decision.
Governor Michele Bullock said arguments for a hold mainly centred around timing, with the four dissenters preferring to wait until May for more information, rather than disagreeing with the direction of travel.
Money markets were pricing in about a 50 per cent chance of a third consecutive rate rise, with economists at all four big banks maintaining their predictions for a May hike.
Domestic price pressures, including a tight labour market and strong economic growth, were already driving inflation further away from the RBA's 2-3 per cent target band before US-Israeli strikes on Iran.
The war, and Iran's retaliatory attacks, led to the closing of the Strait of Hormuz through which about one fifth of global oil supplies transit, and plunged global energy markets into chaos.
If the conflict worsened or was not resolved soon, higher fuel costs would push inflation in Australia even higher, Ms Bullock said in her post-meeting press conference.
But she insisted the reasons for the rate rise were homegrown.
"Higher petrol prices will add to inflation, but they're not the reason for today's decision," she said.
"Inflation was already too high, reflecting the fact that demand is outstripping supply.Â
"Higher fuel costs will not slow demand enough on their own to address this."
While geopolitics was the trigger, weakness in the Australian economy was the underlying cause, argued Deloitte Access Economics partner Pradeep Philip.
"In the public imagination, today's rate hike will inevitably be read as the Reserve Bank primarily reacting to conflict in the Middle East, kick-starting a tightening cycle to battle a new inflationary wave," he said.
"In reality, the meeting was already live well before the conflict began and reflects concerns about the dire state of the supply side of the Australian economy - unable to grow at or above two per cent without breaking out in inflation sweats."
The RBA board and Ms Bullock expressed concerns inflation expectations were rising.
If the bank wasn't seen to be acting quickly, there was a risk it would cause inflation to become entrenched.
Ms Bullock said she understood the bank's decision would be hard to take for mortgage holders dealing with rising petrol prices.
Each 25 basis point rise adds about $90 in monthly repayments to a typical loan of $600,000 on an owner-occupied property.
"But it'll be much worse if inflation gets built into the fibres and then we will see the cost of everything going up," she said.
"That will be a much worse outcome."
The big banks said they would pass on the hikes in full.
Treasurer Jim Chalmers said the RBA's decision would be tough news for millions of Australians with a mortgage.
"We've strengthened the budget over the course of the last three-and-a-half years and there will be more of that in May," he said.
Australian Chamber of Commerce and Industry chief executive Andrew McKellar said the decision could be the final nail in the coffin for many businesses.
"The current fuel crisis only elevates the need to pursue economic reforms that will drive productivity growth, by making it easier to do business and encouraging businesses to invest," he said.
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