"Our Trade Deal with China is moving along nicely, but in the end, we will probably have to use a different structure in that this will be too hard to get done and to verify results after completion," Trump said in a Twitter message.
On Tuesday Trump told reporters that he would not talk about the trade deal, saying "I don't like to talk about deals until they're done."
US Treasury Secretary Steven Mnuchin said on Sunday that the United States and China had both put a hold on tariffs and agreed to a framework for a trade deal.
Tensions between China and the United States had escalated in recent months as US President Donald Trump threatened to slap steep tariffs on Chinese exports to the United States. In response, Beijing vowed to retaliate against US exports to China with a matching value.