Aid groups working with migrants said there had already been an increase in Polish police and armoured vehicles in the area in recent days, and that they were worried the order would limit their work and leave refugees stranded.
"The atmosphere is generally violent, there are uniformed, armed servicemen everywhere...it reminds me of war," said Marta Anna Kurzyniec, a resident of the Polish border town of Krynki.
Poland began building a barbed wire fence last week to curb the flow of migrants from countries such as Iraq and Afghanistan.
The EU imposed economic sanctions on Belarus following a disputed election in August 2020 and a crackdown on the opposition, and says Mr Lukashenko has deliberately encouraged migrants to cross into Poland, Latvia and Lithuania in retaliation.
Belarus' Foreign Minister Vladimir Makei on Thursday blamed "Western politicians" for the situation on the borders, Belarusian state news agency Belta reported.
"Belarus has always honoured all the provisions of our agreements to the letter," Mr Makei told a news conference.
Border situation difficult and dangerous
Polish presidential spokesman Blazej Spychalski said the situation on the border was "difficult and dangerous".
"Today, we as Poland, being responsible for our own borders, but also for the borders of the European Union, must take measures to ensure the security of Poland and the (EU)," he said.
Rights activists have accused Polish authorities of denying adequate medical care to stranded migrants. Warsaw says they are the responsibility of Belarus.
Marysia Zlonkiewicz from the aid group Chlebem i Solą (With Bread and Salt) said police had asked them to stop their activity along the border before the state of emergency was announced.