Two tractors caused long tailbacks on the A92 heading north into Aberdeen on Monday, and there were also protests at the Kessock Bridge in Inverness.
Fuel prices have risen to record highs in recent weeks.
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In England, Rolling roadblocks have brought parts of the M4 to a standstill between Bristol and South Wales, including the Prince of Wales Severn bridge crossing, as part of action calling for a cut in fuel duty.
The protests are understood to have been organised via social media under the banner Fuel Price Stand Against Tax.
They come as latest figures from Experian show the average price of petrol reached a new high of 191.5p per litre on Sunday.
The average price of diesel was 199.0p per litre.
Mobile welder Richard Dite, 44, from Maesteg, South Wales, said it is costing him hundreds of pounds in fuel to get to work every week due to price hikes.
“It’s costing me £300 a week before I even get to work and earn anything,” Mr Dite told the PA news agency.
“My only option soon will be to put the welding gear in the shed and call it a day, maybe go on the dole.
“Face it, at this rate I’ll be on more that way.”
In Wales, protest organisers were told by police before leaving they could not stop and must drive no slower than 30mph.
Both carriageways of the M4 approaching the Severn crossing were brought to a standstill by go-slow protests travelling east and west.
Two police motorcyclists rode in front of four vehicles travelling at around 30mph from the Bristol area towards South Wales.
There was a marked police patrol car behind the protesters, followed by dozens of queuing motorists.
A larger convoy of protesters drove over the Severn crossing heading into England from Wales with a large backlog of traffic following behind.
The AA claimed petrol wholesale costs ended last week 10p down on the record highs of early June.
RAC fuel spokesman Simon Williams said it is time for the Government to “take action” and cut fuel duty again or reduce VAT to help “hard-pressed drivers and businesses”.
Chancellor Rishi Sunak said he will carefully consider calls for a “more substantial” fuel duty decrease after the 5p per litre reduction implemented in March failed to halt price rises.
The Government said that while it understands people are struggling with rising prices and have a right to protest, “people’s day-to-day lives should not be disrupted” and warned that traffic delays “will only add to fuel use”.
Gwent Police said protests are expected to take place on the road network between 7am and 7pm on Monday.
A Government spokesman said: “While we respect the right to protest, people’s day-to-day lives should not be disrupted, especially on busy motorways where lives are put at risk and resulting traffic delays will only add to fuel use.
“The new Public Order Bill will make it a criminal offence to glue yourself to a dangerous motorway, which sees police spending hours trying to safely remove people.”