Donald Trump bragged that they were trying to overthrow the government of Venezuela, to stage a regime change and take their oil. Part of regime change tactics is pretending that Venezuela’s elections are illegitimate. This is just another propaganda piece by the people who want to steal Venezuela’s oil.
But seriously, if you say you won with 51% and refuse to release the detailed results of the election you oversaw, that's on you, no need to blame the US this time. Maduro just demonstrated he's a shitty dictator who can't even fake an election to save face, let alone run the country.