The fund shaved 0.1 percentage point from America's expected GDP this year and 0.4 percentage points from growth through 2019.
The IMF slashed China's growth rate to 6.6 per cent in 2018 and further down to 6.2 per cent in 2019, from 6.9 per cent in the previous year.
U.S. Treasury Secretary Steven Mnuchin is expected to meet with worldwide finance officials in Indonesia this week during IMF and World Bank summits, though as of Monday he had no meetings scheduled with Chinese officials - as reported by Reuters.
US President Donald Trump recently sanctioned tariffs on an additional Dollars 200 billion worth of Chinese goods, nearly 15 per cent of China's total exports to the US.
The IMF is expected to meet this week in Bali, Indonesia for its annual meetings with trade wars and the Federal Reserve's tightening monetary policy being main topics of discussion.
"We are concerned about the downturn in economic growth", noted Jubilee USA Executive Director Eric LeCompte. Furthermore, China's debt to GDP ratio increased by around 100 percentage points, indicating border-lining financial crisis.
But the International Monetary Fund, which released its predictions for the world economic system at its annual meeting in Bali, Indonesia, warned that China's economy could decelerate further if the trade conflict deepens.
The latest of these exchanges saw US President Donald Trump impose a 10 percent tariff on $200 billion (£153 billion) worth of Chinese goods in September, which would increase to 25 percent by the end of 2018.
The IMF report said "protectionist rhetoric" was being "increasingly turned into action", warning that such uncertainty "could lead firms to postpone or forgo capital spending, and hence slow down growth in investment and demand".
The Briton Woode institution is also projecting growth of 1.9 and 0.8 percent for Nigeria and South Africa while it is predicting contraction of 0.1 percent for Angola.
Japan would see its 2019 growth rate more than halved, from 0.9% to 0.4%, under the worst case scenario.
"Not only have some downside risks that the last WEO identified been realized, the likelihood of further negative shocks to our growth forecast has risen".
The Fed's rate hikes have already piled pressure on emerging market economies, increasing the risk of capital outflows as investors seek higher returns.
The Fund's analysts point out that the steady recovery, which has been occurring since mid-2016, continues, while the growth of the world economy for 2018-2019 is projected to remain at the 2017 level.