"The issue of the political divide that exists between the two sides must step by step reach a final resolution and it cannot be passed on from generation to generation," the official Xinhua news agency quoted Xi as saying.
Taiwan and China split amid civil war in 1949. China still claims the democratic island as part of its territory, and insists that it will be brought back into the fold, and has threatened to use force if the island were to declare independence or delay unification indefinitely.
That stance is extremely unpopular on Taiwan, where the great majority of the island's 23 million people have no interest in uniting with the mainland, seeing it as the death knell for their hard-won democratic freedoms.
Ma appeared to acknowledge that in his remarks on Friday, saying he was not considering holding a referendum on a peace treaty with Beijing something he himself says would be necessary before such a treaty could be considered.
"I don't think the time is now right," he said. "I think we can wait."
The peace treaty is favored by China, because it sees its implementation as putting Taiwan on an inevitable trajectory toward unity, the ultimate goal of its Taiwan policy for the past six decades.