"The rest of the world sees perfectly well that Washington's policy is getting increasingly aggressive and reckless," a Russian Foreign Ministry statement said.
Gas prices in the U.S. have risen for nine straight weeks.
Iran's General Amir Hatami said President Donald Trump's policies have promoted "such traits as selfishness, cruelty and violation of humanitarian principles and international rules."
Russian Deputy Foreign Minister Sergei Ryabkov said the new measures are illegal.
Secretary of State Mike Pompeo's warning came despite President Donald Trump's previously expressed optimism about the "great economic potential" of North Korea.
House Democrats can and should expose Trump's failed North Korea policy by questioning Mike Pompeo, John Bolton and Pentagon and intelligence agency officials on national TV.
The president "rejoices over the misery that he thinks he has imposed on ordinary Iranians," Iranian Foreign Minister Javad Zarif wrote on Twitter.
"Other tools have somehow disappeared from U.S. diplomacy's arsenal," Russian Foreign Minister Sergei Lavrov said.
Pyongyang had been hoping for a reduction of sanctions after the summit.
Russian troops will remain in the country "as long as they need it, and as long as the Venezuelan government needs them," Foreign Ministry spokesperson Maria Zakharova told reporters.
"President Trump likes Chairman Kim and he doesn't think these sanctions will be necessary," the Sanders said.
"This is a sure sign of your successful work in Russia," Russian President Vladimir Putin told a director from the country's Ministry of Energy.
"No one can defeat a nation which pursues resistance," Iranian President Hassan Rouhani said in a televised address, claiming the U.S. and its allies were to blame for the country's poor economy.
The U.S. wants to change the regime in Iran, while Europe simply seeks to reform the regime's behavior. But the two parties are closer on some issues than you'd think.
Vladimir Putin's government has already taken steps to protect the Russian economy against such "racketeering attacks," Dmitry Peskov, Putin's spokesman, said.
"It really seems to be getting toward quite a grand scheme," legal expert Harry Litman said, "where officials are feathering their nests."
"It's convenient for them to let the country continue enduring this absurd crisis," an aid worker said.
"Donald Trump has without doubt given an order to kill me and has told the government of Colombia and the Colombian mafia to kill me," the embattled South American leader said.
Venezuelan President Nicolás Maduro refused to submit to what he called "imperialist" international demands for a new election amid his power struggle with opposition leader Juan Guaidó.
"We continue to assess that Iran is not currently undertaking the key nuclear weapons-development activities we judge necessary to produce a nuclear device," Dan Coats said.
"The U.S. government has limited ability to provide emergency services to U.S. citizens" in the country, the advisory warned.
China said, "History has taught us that external interference or sanctions, instead of helping solve problems, can only complicate matters."
"In the face of any aggression, of any nature and intensity, we will defend Venezuela, as it belongs to us," said Defense Minister Vladimir Padrino, who is standing by embattled President Nicolás Maduro.
White House national security adviser warned of a "significant response" to any harm that came to U.S. citizens at the hands of Venezuela.
The State Department is not saying when it will implement the sanctions, noting that there is no deadline in the law for imposing them.