U.S. President Donald Trump said on Monday he was optimistic that a final trade deal could be reached with China and that he would hold a summit to sign any pact, but cautioned an agreement may still not happen.

Speaking at the White House a day after signaling that he planned to meet with Chinese President Xi Jinping to conclude any deal, Trump told a group of U.S. governors that while a U.S.-China trade pact could happen soon, a deal also may not be reached.

"It might not happen at all, OK? Might not happen at all, but I think it's going to happen and it could happen fairly soon. The relationship is great," the Republican U.S. president said. Both sides were "very, very close," he added.

On Sunday, Trump said he would delay an increase in U.S. tariffs on $200 billion worth of Chinese imports, set for Friday, due to "productive" trade talks. Assuming additional progress is made on both sides, Trump said he planned to meet with Xi at his Mar-a-Lago estate in Florida.

World markets rose on Monday after Trump announced the delay in boosting tariffs, feeding investors' hopes that the trade war between the world's two biggest economies could soon be resolved.