Obama on Monday shared his concern over the status of a cease-fire agreement, known as the Cessation of Hostilities in Syria between the government and the opposition parties, Xinhua news agency quoted the White House as saying 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 US and Russia agreed on a plan for a cease-fire in Syria that began on February 27.
The cessation of hostilities was largely envisaged in Munich on February 12 during a meeting of the International Syrian Support Group, which is co-chaired by the US and Russia.
The group is composed of the Arab League, the European Union, the UN, and 17 other countries.
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. (IANS)