The Ukrainian president has been heckled by relatives of 100 protesters killed in Kiev’s Euromaidan revolution at a memorial ceremony for the victims.

The relatives, frustrated by Petro Poroshenko’s failure to bring officials of the previous government to justice, shouted: “Who is a hero for you, Poroshenko?”, “Where are their killers?” and “Down with Poroshenko!” They also attacked him for failing to keep a promise to confer the title of national hero on the victims, which would bring financial benefits to their families.

It was the first real public display of anger against Poroshenko, who was elected in May after the pro-Moscow Viktor Yanukovich fled the country.

The US vice-president, Joe Biden cancelled a planned visit to the area off Kiev’s Independence Square, apparently for security reasons.

Poroshenko and Biden had been due to lay a wreath together at the memorial but instead met nearby and shook hands before the US vice president headed for talks with the prime minister, Arseniy Yatsenyuk.

Speaking afterwards, Biden condemned Russian behaviour in Ukraine as “unacceptable” and urged it to abide by a September peace deal by adhering to a ceasefire and removing military forces from the country.

Addressing himself rhetorically to Kremlin leader Vladimir Putin, Biden said: “Do what you agreed to do, Mr Putin.”

Referring to Russia’s annexation of the Crimea in March and its backing for separatist rebels in eastern Ukraine, Biden, in a statement to the press alongside Poroshenko, said Russian behaviour was a “flagrant violation of the bedrock principles of the international system”.

Biden said the United States would always support a democratic, reformist Ukraine, but he made no specific mention of any fresh aid.

Russia denies arming the separatists or sending its troops across the border.

During his visit, Biden is expected to try to breathe new life into a tattered ceasefire in the east. Since the peace pact was declared on 5 September, more than 1,000 people have been killed in fighting between government forces and Russia-backed separatists, according to the UN.

Yatsenyuk said on Thursday he hoped for an announcement on further US assistance to Ukraine during Biden’s visit after a $53m package announced in September, which included non-lethal military equipment such as night-vision goggles, body armour and radios. But Kiev wants Washington to provide lethal assistance.

Russia has warned against the US arming Ukrainian forces, with the secretary of Russia’s national security council, Nikolai Patrushev, saying the conflict in eastern Ukraine “will grow” if this happened.

Friday marked the first anniversary of the decision by the Yanukovich government to ditch a political and free trade agreement with the EU in favour of renewed trade ties with Kiev’s old Soviet master, Russia.

The move triggered protests from tens of thousands who see Ukraine’s future in the European mainstream. After Yanukovich fled in February, Russia annexed Crimea and backed separatists in the east in a conflict which has killed more than 4,300.

Before the confrontation with the relatives, Poroshenko laid candles with other members of the government on a hill off Independence Square, known as the Maidan, where more than 50 of the estimated 100 dead were killed in late February.

The president was barely audible as he addressed the hostile crowd. “If shouting like this continues, everything we did on the Maidan will have been in vain,” he said.

Poronshenko later returned to pledge that he would sign a decree to officially designate the victims, known as the Heaven’s Hundred, as national heroes.

Elena, 65, whose husband was one of the Heaven’s Hundred, burst into tears. “I don’t know why it’s taken so long, but now at last they’ve been recognised … They died so Ukraine could live.”