“I’m ashamed of my country, I’m ashamed of my President and I’m ashamed of myself that I haven’t done more to help these people,” he told CBS’ Face the Nation.
“It is really, really heartbreaking.”
The United Nations conservatively estimates more than 5,700 people have been killed in the war since April.
McCain is in the camp that thinks the U.S. should send lethal weapons to Ukraine’s military, but President Barack Obama hasn’t made a decision yet.
“The Ukrainians aren’t asking for American boots on the ground; that’s not the question here,” he said.
“They’re asking for weapons to defend themselves, and they are being slaughtered and their military is being shattered.”
Ukrainian forces fought their way out of the strategic rail hub of Debaltseve last week, suffering a brutal and bloody defeat.
The Arizona senator also made a quick dig against German Chancellor Angela Merkel and French President François Hollande, who recently helped broker the cease-fire deal in Minsk.
The two have “legitimized for the first time in 70 years the dismemberment of a country in Europe,” he said.
McCain later added that Russian President Vladimir Putin “wants Ukraine not to be a part of Europe and he is succeeding at doing so.”