No, it wasn't.
Market manipulation, legally, is the act of artificially inflating or deflating the price of a security or commodity to mislead other investors and create a false appearance of market activity, ultimately benefiting the manipulator. It involves creating artificial supply or demand, often through deceptive means, to gain an unfair advantage
The price went up and down because of real buys and sells.
Every time the President signs a bill or has an Executive order it can impact the market. The idea that Trump placing tariffs on foreign countries being "market manipulation" would make every single president guilty of this. It shows how idiotic some of our senators and congress people are that they would even ask this question.