"I expressed our condolences during the telephone conversation with Israeli President Isaac Herzog. I also offered him humanitarian assistance," Duda said on air of Polish channel Polsat.
At the same time, the Polish leader urged not to "overestimate the seriousness" of the situation in Israel, saying that it is not the first military conflict in the Middle East over recent decades.
"I would not exaggerate [the seriousness]. This is not the first military situation in the Middle East. We remember that in recent decades such situations have already taken place. The wars that had been waged there did not result in any world wars, so I would not go that far," Duda added.
Earlier in the day, Polish Defense Minister Mariusz Blaszczak said that the Polish military was preparing to evacuate Polish citizens from Israel.
The Israeli government announced earlier on Sunday that it had invoked Article 40 of the Basic Law, which means the country officially entered a state of war.
Israel was hit by an unprecedented rocket attack from the Gaza Strip on Saturday morning. The Israeli army said Hamas fired more than 3,000 rockets, adding that dozens of Hamas troops infiltrated border areas in southern Israel. The Israeli military has since sent troops to the southern territories to reconquer them from the Palestinian forces and has started conducting strikes at Hamas' positions in Gaza.