WASHINGTON — President Obama had “an intense conversation” with President Vladimir V. Putin of Russia on Monday in which he expressed concern on the eve of his visit to the Middle East and Europe about the fragile Syrian peace talks and increased violence in Ukraine, White House officials said.

In a strongly worded statement, the White House said that Mr. Obama had urged Mr. Putin to use his influence with President Bashar al-Assad of Syria to press him to stop attacks against opposition forces and abide by his commitment to a partial cease-fire.

The so-called cessation of hostilities, brokered by Russia and the United States in February, has shown signs of crumbling in recent days, with increasing ground clashes and airstrikes. Syrian government forces have been mounting an offensive near the northern city of Aleppo, while rebel groups have reportedly made advances against government positions in the areas of Latakia in the north and Hama in the center of the country.

A statement released by the office of Mr. Putin said he had stressed the need for moderate opposition leaders in Syria to distance themselves from the Islamic State and other extremist groups.