Galbas called for unity and calm during Independence Day celebrations.
He said prayers would be offered at a mass in Warsaw on Tuesday for the victims of the Kraków attack and those who helped during the tragedy.
The service will take place at 9 a.m. at the Temple of Divine Providence, one of Poland’s main religious venues in the capital.
Galbas invited the public to attend and also appealed to participants in Wednesday's Independence March in Warsaw and other public gatherings to remain calm and mark the national holiday with dignity.
"We need to stand together, especially now, rather than against one another. We need to talk to each other, not shout at each other," Galbas said.
He added that differences in political views and visions for Poland should not become a source of division.
The archbishop said Poles had not approached Independence Day with such sadness and a sense of distress for a long time.
Deadly attack in Kraków
The appeal follows a deadly incident in Kraków on Saturday when a 24-year-old man drove onto the city's main market square and opened fire on passers-by with an automatic weapon.
Six people were killed and 16 injured, including two police officers.
Photo: PAP/Łukasz Gągulski
The seventh fatality is the attacker himself, who was shot during an exchange of fire with police officers and died in hospital on Monday.
Police also found the bodies of three members of the suspect’s family - his parents and sister at their home in the south-central town of Ostrowiec Świętokrzyski.
An official period of mourning in Kraków will remain in force through November 11.
A period of nationwide mourning, declared by President Karol Nawrocki, began on Sunday and continued until the end of Monday.
(pg/gs)