In an interview with public broadcaster Polish Radio, Mariusz Błaszczak said the previous night "was not peaceful" but saw "multiple attempts to break through the Polish frontier."
He added that, according to reports from the army and the Border Guard agency, "all those who managed to pass through have been detained."
Błaszczak also said in the interview that migrants had changed their approach, Polish Radio's IAR news agency reported.
"Two days ago, we saw a single, large group of migrants ... trying to force its way through the border en masse, whereas now they are attacking the frontier simultaneously in various smaller, but still sizable groupings," Błaszczak said.
Meanwhile, military support for the border guards has been increased to 15,000 troops and could rise further if necessary, Błaszczak announced.
"Our security forces and law enforcement agencies are prepared to ensure our homeland is secure," he declared.
Belarusians 'intimidating migrants': Polish defence ministry
His defence ministry tweeted a video that it said depicted how Belarusian security services "are intimidating migrants by firing shots in their presence."
Another video posted on Twitter showed Belarusians committing "acts of violence" against migrants, according to the Polish defence ministry.
Later on Wednesday, European Council President Charles Michel was expected to visit Warsaw for talks with Poland's Prime Minister Mateusz Morawiecki as the country remained under migrant pressure from Belarus.
On Tuesday, Morawiecki told lawmakers the migrant crisis was the most serious security risk facing Poland in decades, state news agency PAP reported.
Polish border guards, police and soldiers on Monday thwarted several attempts by migrants to force their way into the country via Belarus, government officials said, as the border crisis escalated.
EU, NATO, US condemn Belarus
The United States on Monday voiced concern over "disturbing images and reports" from the Polish-Belarusian border, and condemned Belarus for "orchestrating" migrants flows to Europe.
NATO condemned the use of migrants by Belarus "as a hybrid tactic," with its Secretary-General Jens Stoltenberg voicing solidarity with Poland amid the border standoff.
Meanwhile, European Commission head Ursula von der Leyen called for EU member states to approve new sanctions against Belarus, which she said was responsible for a "hybrid attack" on the Polish border using migrants.
The European Union has accused Belarus of encouraging thousands of migrants from the Middle East and Africa to cross into EU countries via Belarus, as a form of hybrid warfare in revenge for Western sanctions on Minsk over human rights abuses, the Reuters news agency reported.
Poland and the Baltic states have accused Belarus's strongman leader Alexander Lukashenko of organising a wave of illegal migrants seeking to enter the bloc as part of what officials have called a "hybrid war."
The EU Commissioner for Home Affairs, Ylva Johansson, visited Poland in late September, agreeing with Warsaw’s arguments that “firm steps” were needed against Belarus, according to officials.
Poland's Morawiecki said last month that his country enjoyed full support within the European Union as it worked to defend itself against a migrant influx and a "hybrid war" being waged by Belarus.
In late September, Polish lawmakers voted overwhelmingly to extend a state of emergency in parts of two regions along the country's eastern border with Belarus by two months amid a growing migrant surge.
The state of emergency gives authorities broader powers to monitor and control the movement of people on the Polish-Belarusian border, which is also the eastern border of the European Union.
Source: IAR, PAP