Maduro made the announcement on state TV, surrounded by military commanders before opposition leaders led by Juan Guaido vowed to bring in USA supplies of emergency food and medicine over the socialist president's objections.
A US envoy is heading to Colombia as part of a mission to send food and other emergency supplies to neighboring Venezuela amid a deepening political and economic crisis there.
After the Brazilian government pledged to also send aid in, Maduro declared that the Venezuelan government would close the border with Brazil on Thursday night. Pence will meet with Colombian President Ivan Duque as well as Venezuelan families who have sought refuge outside the country.
"We know that the regime is going to put all obstacles to prevent us from reaching the border, but nothing is stopping us, we are going to continue", said opposition lawmaker Yanet Fermin. The economy's size has halved over the past five years.
Guaido still has not provided details on how the aid could come in.
Under Maduro's orders, Venezuela this week blocked air and sea travel between Venezuela and the Dutch Caribbean island of Curacao.
Civilians prompt delay in assault on last Daesh enclave: Kurd-led forces
Hungarian Foreign Minister Peter Szijjarto said the issue is "one of the greatest challenges ahead of us for the upcoming months". He then reiterated his claim that " The Caliphate is ready to fall ". "They're not talking to each other as much", he added.
"Starting February 21, 20:00 (03:00 Moscow time on Friday - TASS), the land border with Brazil will be fully closed", he said during a speech transmitted via Periscope.
Bernie Sanders, a self-avowed Democratic socialist, refused to call for Venezuelan leader Nicolás Maduro to step down Thursday.
Maduro accuses the Trump administration, which recognizes Guaido and has levied crippling sanctions against the Venezuelan government, of seeking to force his ouster.
Some political analysts say Saturday's border showdown is less about resolving Venezuela's needs and more about testing the military's loyalty by daring it to turn aid away.
Guaido has offered amnesty to military officers who disavow Maduro, though few have so far done so.
Maduro's decision follows the action taken by opposition leader Juan Guaido in defiance of Maduro.