KIEV, Ukraine — A week into a cease-fire between pro-Russia separatists and government forces in the east of Ukraine, President Petro O. Poroshenko said on Friday that the pact appeared to be growing stronger by the day, in remarks that conspicuously avoided direct criticism of Moscow.

Mr. Poroshenko, who has been trying to generate a sense of momentum for a lasting truce in the rebellious eastern region, repeatedly emphasized that his government wanted a peaceful settlement to the crisis, even as both the European Union and the United States enacted new sanctions to punish Russia for its role.

The president and other senior officials, addressing a forum about the crisis, emphasized the arduous work ahead to make the peace stick.

“The next stage will be a very difficult road,” said Valeriy Chaly, one of the president’s leading advisers on foreign policy. Both the president and Mr. Chaly noted that the leaders of Russia, Ukraine, France and Germany were scheduled to hold a group telephone call on Saturday about how to strengthen the truce. The four first gathered in Normandy this year during World War II commemorations.