The United States has led the sanctions campaign to press North Korea to give up its nuclear and missile programs.
North Korea's nuclear weapons program has caused global tension for decades and the rhetoric and threats from Kim and Trump had been especially hostile before their June meeting.
"However, the US responded to our expectation by inciting global sanctions and pressure against the DPRK", it said in a statement carried by KCNA news agency.
The unidentified spokesperson also warned that there is no guarantee that the hard-won atmosphere of stability on the Korean Peninsula will continue.
Iranian President Hassan Rouhani told North Korea's foreign minister that the United States can not be trusted, Tehran's state media said, as the United States seeks a deal to rein in the North's nuclear and missile programmes.
"They made public the North Korea Sanctions and Enforcement Actions Advisory; and additional sanctions".
Earlier this month, U.S. Secretary of State Mike Pompeo warned Russia, China and other countries against any violation of global sanctions on North Korea that could reduce pressure on the North to abandon its nuclear weapons.
North Korea rejected USA appeals to give up part of its nuclear arsenal and reaffirmed its friendship with Iran yesterday as the fragile detente between the two nuclear powers began to disintegrate.
The warnings come just days after North Korea's foreign minister called U.S. actions "alarming".
Seoul said it accepted the North's proposal after Pyongyang first suggested a meeting Monday to discuss another summit between the leaders.
Relations between North Korea and the U.S. remain tense, despite reassurance from the U.S. State Department that the two countries are in contact with each other.
It wasn't clear when another inter-Korean summit might happen, but if the April 27 summit agreements between Moon and Kim are followed through on, the leaders will likely meet in Pyongyang in the next couple of months.
The Korean Peninsula is still technically in a state of war because the 1950-53 fighting ended with a ceasefire, not a peace treaty.
"In the current situation, friendly countries should develop their relations and cooperation in (the) worldwide community", he said, adding Iran and North Korea have "always had close views" on many issues. Russian Federation and China have suggested the U.N. Security Council could discuss loosening sanctions on Pyongyang after the June 12 Singapore meeting between Trump and Kim.