"There is no justification for the closure of the Rafah crossing," Hamad al-Raqb, a spokesman for the protesters, said in a speech marking the beginning of a four-day sit-in.
"It is unbecoming of the historic relations between Egyptians and Palestinians," he insisted.
Leading Hamas figures and MPs attended the launch ceremony.
Egyptian authorities have tightened their control over the border with the Hamas-run Gaza Strip since last July's ouster of elected president Mohamed Morsi by the Egyptian army.
In recent weeks, Egypt has repeatedly closed the Rafah crossing, which – due to an ongoing, eight-year Israeli siege – represents Gaza's only window to the outside world.
The Egyptian army has also launched a campaign aimed at destroying the network of tunnels linking Gaza to Egypt's Sinai Peninsula, which in recent years had been used to bring vital commodities into the besieged coastal enclave, home to nearly 2 million Palestinians.
Hamas, an ideological offshoot of the Muslim Brotherhood, the group which propelled Morsi to power in the 2012 elections, has controlled the Gaza Strip, since 2007.
New Unified Combatant Command 'will strengthen our cyberspace operations'
Opposition lawmakers refuse to attend session announcing decree
The 15 council members held the commemoration at the start of a session dedicated to the crisis in Yemen.
Catalonia police spokesman Josep Lluis Trapero added that a driver who mowed down crowds of pedestrians in the first attack in a busy Barcelona street Thursday could be among five suspects later shot dead in a nearby city.
Massoud Barzani, General Joseph Leonard Fotel discuss fight against ISIL, planned referendum on region’s independence
Sergey Lavrov, Sigmar Gabriel say there is 'no alternative' to political, diplomatic solutions
UN agency says civilians in South Sudan keep flocking to Ethiopia as fight between government forces, rebels continues
Around 1,000 migrants, refugees to be moved to 18 sites across Ile-de-France region
Victim's name will not be released until family is informed, says Turkey's embassy in Madrid
For his part, Interior Minister Gerard Collomb told RTL radio that "the number of those who have been seriously injured may perhaps be even higher at around 17."
New York Police Department officials said the force would hold a press conference but declined to provide scheduling details.
Death toll feared to rise due to severe conditions of the many injured
The pickup truck, which had an improvised white wooden trailer constructed over the back, was transporting them in "overcrowded and unsanitary conditions," said a state police report seen by AFP.
At least 13 people were killed and more than 50 injured when a driver deliberately slammed his vehicle into crowds on Barcelona's most popular street -- Las Ramblas -- in what police qualified as a "terror attack."
The van attack that mowed down pedestrians on Barcelona's most famous street on Thursday killing at least 13 people was the latest fatal assault on a European city.
The agreement to open the market potentially worth $10 million a year came after US Vice President Mike Pence met this week with Argentina's president Mauricio Macri.