CNBC's Jim Cramer said Wednesday that President Donald Trump's optimistic morning tweet on China trade talks was aimed at Wall Street and Beijing.

"This is about getting the Dow up a little bit but also pressuring [China], " said on "Squawk on the Street" before the opening bell "You put this tweet out because some of the price-weighted stocks in the Dow will rally."

Dow futures were sharply lower for a third straight session before Trump tweeted that Chinese negotiators "just informed" the White House they are "coming to the U.S. to make a deal" on trade.

Trade talks were set to get continue in Washington on Wednesday, under the U.S. threat of increased tariffs on Chinese imports from 10% to 25% come midnight Friday.

Immediately after the president's tweet, Dow futures briefly turned positive before dipping modestly into the red. The Dow Jones industrial average opened slightly lower and then even spent some time in the green.

"This is all we do. We parse" tweets from Trump, Cramer said, questioning what to believe. "It's amazing how these things matter."

On "Mad Money" Tuesday evening, Cramer talked about the Dow stocks most impacted by trade: Apple, Boeing, and Caterpillar. He said Boeing and Apple might not be as vulnerable as they appear because Boeing has lots of orders in the pipeline and Apple's focus more on services puts less emphasis on iPhone sales in China.

Cramer reiterated Wednesday a theme he touched on Tuesday, advising investors to "sit on your hands at this point" — don't buy or sell stocks because the climate is too volatile.