Venezuelan President Nicolas Maduro has slammed sanctions imposed by the US government against the South American country for holding a controversial constitutional assembly election amid violent protests.

"You're with Trump or you're with Venezuela, you're with Trump or you're with the democracy, you're with Trump or you're with the free people of the world, that's the decision, you're with Trump or you're with the free world," Maduro said on Monday in a televised speech.

"They are the decisions that express their impotence, their despair, their hatred. They express the character of the magnate, who is emperor of the US." 

Maduro also responded to Washington's threat to suspend the National Constituent Assembly (ANC), a body that the President created to rewrite the nation's constitution, saying: "I do not obey imperial orders of foreign governments".

"Trump is more disowned in the US and in the world than (former US President) George W. Bush," who declared himself 'anti-colonialist, anti-racist' and against the Ku Klux Klan that rules the White House," the Venezuelan leader said.

US National Security Adviser Herbert R. McMaster on Monday announced direct sanctions by the US government, including freezing Maduro's assets in Washington and prohibiting American citizens from carrying out economic transactions with the Venezuelan leader.

"Maduro is not just a bad leader. He is now a dictator," said McMaster, adding that Maduro has joined "a very exclusive club", that includes Zimbabwean President Robert Mugabe, Syrian President Bashar al-Assad and North Korean leader Kim Jong-un, who have all been sanctioned by Washington.

The US imposed sanctions in response to the July 30 elections of representatives of the Constituent Assembly that Maduro planned to use to draft a new national charter.

However, the opposition and other social societies criticized the move as a way for Maduro to consolidate a dictatorship in the country.

The US along with other South American nations and the European Union (EU) have said they will not recognise the assembly established from the vote.

The Venezuelan Attorney General said rge July 30 protests against the elections left a total of 10 persons dead, however the opposition alliance Democratic Unity Roundtable (MUD) said the toll was 14.

The latest victims bring the total death toll from the wave of anti-government protests that began on April 1 to 121 with over thousands others injured.

The government said more than 8 million Venezuelans voted in the July 30 elections. The MUD refused to participate as it considered the vote "fraudulent".