While an official in Caracas said sanctions are an act of war, a top U.S official said the measures will have no direct impact on oil revenue for Venezuela.

President Barack Obama issued an executive order Monday that sanctions seven Venezuelan officials for human rights offenses. A White House spokesman said the Obama administration is "deeply concerned" by the culture of political intimidation in Caracas.

"Venezuela's problems cannot be solved by criminalizing dissent," the spokesman said.

President Nicolas Maduro has faced mounting pressure from his opponents at least since taking the reins in Caracas after his predecessor Hugo Chavez died in 2013.

María Corina Machado, a former assemblywoman who helped lead protests against Maduro last year, recently called on Pope Francis to step in to a fracturing Venezuela.

Diosdado Cabello, speaker of the Venezuelan Congress, said Monday the sanctions on government officials in Caracas were an open threat from Washington. He called on all Venezuelans to "strongly reject the pretensions of North American imperialism, because what comes next ... are the [military] attacks on our land [and] our country."

The White House dismissed allegations from Caracas, saying the government there has a long history of blaming Washington for internal problems. A senior administration official said in a background briefing with reporters the sanctions have nothing to do with energy.

"In terms of the impact that it may have on the energy sector or the oil industry, there's no direct effect from these sanctions," the official said.

The United States and Venezuela are regional adversaries whose economies are linked nonetheless through oil. Venezuela is the No. 4 crude oil exporter to the United States, though the level of exports is down about 15 percent from 2014.

The International Monetary Fund last month said the low price of crude oil is creating fiscal pressures for countries that rely heavily on revenue from exports. The economic situation in Venezuela was described by the IMF as "precarious."

The Central Bank of Venezuela in December said the collapse in oil prices was in part to blame for a 2.3 percent drop in third quarter gross domestic product, sending the country into a formal recession.