Interior Minister Nestor Reverol said the group, which he said originated in Colombia, attempted to land with fast boats before dawn in the northern coastal state of La Guaira but were intercepted by the military and special police units.
"Thanks to the opportune, effective action of our Bolivarian Armed Forces and special police action forces of the National Bolivarian Police, some were shot down and some were detained," he said on state television.
Reverol gave no details on the number of people detained or killed in the operation, which he said was still underway, with a massive search on air, land and sea.
Venezuela frequently accuses Colombia of fomenting plots to overthrow the Maduro government, and of allowing "mercenaries" to train in its territory.
The Colombian government of President Ivan Duque has denounced Maduro as a "dictator."
Under Maduro, the once oil-rich South American country has spiraled into the deepest economic crisis in its history, one accentuated by US sanctions and now the coronavirus pandemic.
Millions of its citizens have migrated abroad -- many of them to neighboring Colombia -- to escape deepening poverty and repression.
But so far, Maduro has weathered challenges to his rule, notably from opposition leader Juan Guaido, who declared himself acting president in January 2019 with the backing of the United States and more than 50 other countries.
Reverol claimed the group planned to carry out "terrorist attacks," including assassination of regime leaders.
The plan aimed "to increase the spiral of violence, generate chaos and confusion ... and with that lead to a new attempt at a coup d'etat," he said.