The Polish foreign ministry said a Polish-Jordanian family was among those affected by the attack in Jordan's Kerak province.
The Reuters news agency reported that unidentified assailants opened fire at a church in the village of Hamud in western Jordan on Friday.
"Poland strongly condemns the terrorist attack on a church in Jordan's Karak province on October 23. The perpetrators must face the consequences," the Polish foreign ministry said.
"We express our condolences to the families of the victims," it said.
"We stand united with Jordan’s authorities and the Christian community of the Karak province," the statement also said.
"We extend our sympathies to the Polish–Jordanian family which also suffered during the attack," it added.
Local media reported that two attackers entered the church in Hamud, about 120 kilometres from the capital, Amman, and opened fire on people attending a funeral.
Some of the wounded were in critical condition, reports said.
The Kerak province is home to members of the Melkite Church, one of the Eastern Catholic churches.
Its faithful recognise the authority of the pope and follow the Byzantine rite, with Arabic used as the liturgical language, Polish state news agency PAP reported.
The Polish foreign ministry described Jordan as "an important partner" for Poland "in combating terrorism and extremism" and highlighted the country's role in interfaith dialogue and as a guardian of Christian and Muslim holy sites.
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Source: IAR, PAP, Reuters