Protesters were seeking a special diesel rate for professional hauliers, as well as a levelling-out of fuel prices with neighbouring Spain, where diesel is cheaper.
Manuel Pinho, Portugal's economy minister, said the measures agreed on Wednesday would "allow hauliers to adapt to the rise in fuel costs".
Spain protest
Meanwhile, stores in Madrid, the Spanish capital, were having problems filling their shelves on Thursday, as the truckers strike across the country went into its fourth day.
One shopkeeper suggested the shortages in the shops were due to people panic-buying.
She said: "The shelves are a bit empty because people have wanted to get everything. People have gone psychotic, not me.
"It seems the shelves are empty because people have begun to buy without thinking."
Spanish authorities said motorways that had been clogged by striking truckers were now clear, but unions behind the four-day-old stoppage are vowing to fight on.
In a statement released on Thursday, the interior ministry said that police had escorted more than 6,000 trucks transporting food, fuel and other essentials.
The government has signed an agreement with non-striking unions representing the vast majority of the trucking industry.
It calls for tax-relief and other measures to offset soaring fuel costs.
But two striking unions have refused to sign the deal, saying they were sticking by demands for minimum, guaranteed rates for their services.
Truckers in the Netherlands are also blocking motorways in protest at high fuel prices.
On 18 motorways in the country, truckdrivers drove 50km an hour for half an hour on Thursday in order to disrupt traffic.
Brussels rally
Several thousand workers also rallied in Brussels to protest against rising prices and decreasing purchasing power.
A crowd of 6,000 Belgian trade union members demanded lower electricity, fuel and food prices.
The protest blocked traffic and disrupted public transportation in areas around the capital.
"It's getting tough for people," said Mark Leemens, a national secretary for confederation of Christian trade unions.
"Gas and electricity are getting more and more expensive, meaning trouble not only for people on low wages but increasingly also for the middle class," Leemans said.
The rally followed other similar protests around Belgium.
Inflation in the euro zone is running at the highest level since 1996.