Putin: 'Only on equal terms'
Putin said Russia had been obliged to annex Ukraine's Crimea region in March in order to prevent NATO forces entering, which would have created "a completely different alignment of forces."
He told the diplomats that they would "face growing pressure in defending national interests" and that "the events provoked by the West in Ukraine have become a concentrated political expression of deterrence toward Russia."
Putin also referred to Russia's tense relationship with the United States, suggesting that the current crisis was born of the West's attempts to impose its own way of doing things on the rest of the world.
"Our relationship with the United States is not the best at the moment," he said.
"We have always tried to be predictable partners, handle business on an equal basis, but in return our legal interests were partially ignored and are still ignored. Russian and U.S. contacts have a great meaning for the entire world.
"We are ready for constructive dialogue, but again I emphasize only on equal terms."
Russia's ambassador to the European Union, Vladimir Chizhov, said Tuesday that the refusal to extend the cease-fire is a "negative sign," the Russian Foreign Ministry said on Twitter.
"This makes it even harder to understand the logic of how the confirmation of the so-called 15-point peace plan correlates with the refusal to prolong truce," Chizhov was quoted as saying by state news agency ITAR-Tass.
'Enemies and invaders'
Poroshenko declared in a late-night televised address that the cease-fire was over.
In Kiev's Independence Square, known as Maidan, activists outside the presidential administration building applauded Poroshenko's stance.
"We need only military actions," a priest named Valentyn said in a Reuters interview. "We were forced by those who entered our country as enemies and invaders."
The crisis has its roots in former President Viktor Yanukovych's decision last year to shun a European Union Association Agreement and turn toward Russia instead. The move unleashed deadly strife that led to Yanukovych's ouster, Ukraine's loss of Crimea, and a pro-Russia separatist rebellion. Russia also massed troops along its western border with Ukraine.
The Association Agreement, which will bring closer trade and political ties between Ukraine and Europe, was finally signed by Poroshenko and European leaders last week.
After Monday's phone call, Poroshenko said his goal was peace but insisted it takes the participation of all parties to maintain stability, noting violations of the cease-fire by pro-Russia separatists.
The Ukrainian government "has been completely fulfilling its commitments and unilaterally complying with the ceasefire regime for 10 days and paid dozens of lives for that," he said.
Peace talks were held last week among Ukrainian government officials, pro-Russia separatists from the restive eastern Luhansk and Donetsk regions, Russian officials, and members of the Organization for Security and Cooperation in Europe.
Activist Vadym told Reuters there was no point in continuing the cease-fire.