"I thought that [stock] futures would open down big," Cramer said Monday on "Squawk on the Street." "By not being down, the market is saying, 'Trump's right.' It's not saying [trade] doesn't matter. It's saying Trump's right."
Trump's criticism came shortly after he left the G-7 meeting in Quebec early to travel to Singapore for a historic meeting with North Korean leader Kim Jong Un.
The president decided earlier this month to impose tariffs of 25 percent on steel imports and 10 percent on aluminum imports from Canada, Mexico and the EU. The three U.S. allies quickly announced retaliatory measures.
Cramer on Friday cautioned against trading around Trump's tweets and his administration's talks with U.S. trading partners. He contended at the time that trade talks were "a work in progress," saying investors should buy on trade-related downturns rather than fret about them.
"Think of it this way: we've had the best action in three months for the Dow and that occurred ahead of the Fed meeting, ahead of the G-7 meeting and ahead of the North Korean summit," Cramer said Friday. "Worry has not been paying off here."
Cramer said Monday there are some people on Wall Street who believe the market doesn't take Trump seriously. The "Mad Money" host is not one of them.
"If they didn't think Trump was serious, if they didn't think the president mattered ... then the market would be down big," Cramer argued.