Earlier in April he asked tens of thousands of people at the end of a Mass in St. Peter's Square to share their money as a "gesture of charity", according to Reuters.
Violence has intensified recently in eastern Ukraine between government forces and Russian-backed rebels.
Since it began in 2014 more than 9000 people have been killed and more than a million have been displaced.
It started when pro-European protesters toppled the pro-Russian government led by former President Viktor Yanukovych.
The ousting followed Mr Yanukovych's decision in November 2013 to leave a deal with the European Union to instead create stronger ties with Russia.
Ukraine has been stuck in a conflict between east and west since the collapse of the Soviet Union in 1991.
The vast majority of Christians living in Ukraine are Orthodox, but there are about a million Roman Catholics.
Pope Francis has not yet specified how the aid would be distributed.
