The accusation came after Washington urged Cambodia to reverse a ban on the Cambodia National Rescue Party (CNRP), saying the decision was a setback for democracy that would strip next year's elections of legitimacy.
On Thursday, Cambodia's Supreme Court dissolved the CNRP and banned more than 100 of its politicians, accusing the party of trying to topple the government.
A spokesman for Cambodian Prime Minister Hun Sen’s ruling Cambodian People's Party (CPP) said Friday the decision to dissolve the party was in line with the law.
Sok Eysan also downplayed US threats to end support for the country, calling Washington the "ringleader" of the CNRP's alleged coup plot.
"If the EU and US won't assist us, there are countries like Russia, China, Japan and South Korea who would help us continue the democracy," he said.
The Thursday ruling, which essentially allows Hun Sen's party to run uncontested in next year's elections, has sparked condemnation from the US, the European Union and the United Nations.
The Supreme Court verdict is reportedly the latest in a long crackdown by the government on dissent that has seen the CNRP president Kem Sokha jailed for treason in September and media outlets shuttered, journalists jailed and activists harassed.