NAIROBI, Kenya — Kenya’s top political rivals met on Friday for the first time since last summer’s contentious presidential elections, a surprising turn after months of escalating tensions, and the start of what they called a jointly led push for national unity.

“This marks a new beginning for our country,” President Uhuru Kenyatta said at a news conference, alongside the opposition leader Raila Odinga. “We may differ in political alignment but we should unite as Kenyans in matters that affect the country.”

Mr. Odinga said: “The reality is, we need to save our children from ourselves.” He called Mr. Kenyatta “my brother,” and said the two had come together to bridge the country’s generations-old differences.

“We refuse to be leaders under whose watch Kenya slid into a failed nation,” he added.

Their remarks represent a significant turn of events, coming little more than a month after Mr. Odinga, who lost last year’s presidential election, swore himself in as the “people’s president.” The government responded by shutting down television stations, arresting opposition politicians and deporting an opposition lawyer, defying court orders along the way.