"Please leave Iran immediately and under no circumstances travel to that country,” Prime Minister Donald Tusk said.
He told reporters he did not want to "cause alarm" but said that the possibility of a “hot conflict” in the country was "very real."
He added that "in a matter of hours" evacuation may no longer be feasible.
He appealed to citizens to treat his warning seriously, saying that in the event of open conflict, no one would be able to guarantee evacuation options for Polish nationals.
Tensions in the Middle East have escalated in recent weeks. US President Donald Trump has repeatedly threatened Iran with intervention, including possible military action, according to reports.
The United States has increased its military presence in the region, while Iran has said it would retaliate against US military installations if attacked, Polish state news agency PAP reported.
US broadcaster CBS News reported on Wednesday that the Pentagon was temporarily relocating some personnel from the Middle East to Europe and the United States amid concerns over a potential US strike on Iran and possible retaliation from Tehran.
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Source: TVP Info, IAR, PAP