Poland's foreign ministry has confirmed that the man is injured but that his life is not endangered.
The ministry has clarified that until now two Polish citizens have died as a result of the shootings at Tunis's Bardo Museum. Ten are injured and one is still missing.
All in all 23 people died in the incident, including two gunmen who were shot down by counter-terrorist police.
The Islamic State jihadist organisation claimed responsibility for the attack via an audio message posted online on Thursday.
"Two knights from the Islamic State... heavily armed with automatic weapons and grenades, targeted the Bardo Museum," the message stated.
"What you have seen is just the first drop of rain."
Close to 3,000 Tunisians are estimated to have taken up arms as jihadists in Iraq and Syria, according to the International Centre for the Study of Radicalization in London. The number is larger than that of any other national group.
Tunisian lawyers place flowers during a protest outside the National Bardo Museum in Tunis, Tunisia on 19 March 2015. EPA/MOHAMED MESSARA
Meanwhile, Polish citizens who were in Tunisia are returning in droves to Poland on flights covered by the foreign ministry.
182 Poles returned late on Thursday night to Warsaw, including 20 who had been caught up in the terrorist attack.
Tusk on terrorist threats
President of the European Council, former Polish Prime Minister Donald Tusk has said that there is no need for EU heads of state and government to issue manifestos in the wake of the terrorist attacks in Tunisia.
Addressing reporters in Brussels, he said that what they should do is to step up work on the package of documents adopted last month, after the terrorist attacks in Paris.
In February they advocated a better implementation of the instruments that are already in place, as well as an adoption of a directive on the exchange of Passenger Name Records, which is currently under debate in the European Parliament.
On Ukraine, Mr Tusk said that the European Union should keep economic sanctions on Russia in place until a ceasefire deal in fully working. (nh/mk)
PAP/IAR/AFP