WASHINGTON, April 18 (Xinhua) -- U.S. President Barack Obama and his Russian counterpart Vladimir Putin discussed Syria and Ukraine in a phone call on Monday, the White House said.

Obama shared his concern over the status of a cease-fire agreement, known as the Cessation of Hostilities in Syria between the Syrian government and the opposition parties, the White House said in a statement.

The two presidents also "committed to intensify their efforts to shore up the Cessation of Hostilities" and agreed on the need to end attacks by all parties.

The United States and Russia agreed on a plan for a cease-fire in Syria that began on Feb. 27.

The cessation of hostilities was largely envisaged in Munich on Feb. 12 during a meeting of the International Syrian Support Group, which is co-chaired by the United States and Russia.

The group is composed of the Arab League, the European Union, the United Nations, and 17 countries including China.

On Ukraine, Obama urged Putin to "take steps" to end the fighting in eastern Ukraine and stressed the importance to move forward with full implementation of the Minsk agreements.