British media reported that the Poles were Angelika and Marcin Klis, parents of Alex Klis, who after the explosion put out an appeal on Facebook for information about the couple's whereabouts.
At least 22 people, including children, died and some 120 were wounded in a blast as thousands of fans streamed out of a concert by US pop singer Ariana Grande at the Manchester Arena on Monday night. The sports and concert hall has a capacity of 21,000.
"Two Poles, who we had been searching for unfortunately did not survive the attack," Polish Foreign Minister Witold Waszczykowski said on Wednesday.
"Two girls... were at the concert. Their parents arrived to pick up their daughters and, unfortunately, this morning we received news that they did not survive the explosion," Waszczykowski said.
Top Polish officials have sent condolences to the family of the deceased Polish couple.
"To the family of the murdered I send my deepest condolences," Polish Prime Minister Beata Szydło said on Twitter. "Innocent people die at the hands of ruthless murderers," she added.
Polish President Andrzej Duda said: "I join the loved ones of my compatriots who died in the attack in Manchester in grief and prayer. My thoughts are also with the injured Pole."
Many Polish familes live in the Manchester area, with some 20,000 Polish-language speakers in the region.
On Tuesday, the ISIS-affiliated Amaq news agency reported that the so-called Islamic State was behind the explosion.
British police on Tuesday confirmed media reports that the attacker was 22-year-old Salman Abedi, a Briton of Libyan descent, who, according to Britain's The Daily Telegraph, was born in Manchester to refugee parents.
UK police said that they were investigating whether Abedi acted alone.
Top Polish officials have condemned the attack, sending their condolences to the UK. (vb/pk)