Mr Trump made the remarks during a press conference on Friday, saying that while the incident was “tragic”, the press should focus on China over Russia.
The president said: “So, I don’t know exactly what happened. I think that it is tragic. It is terrible. It should not happen. We have not had any proof yet, but we will take a look. … I would be very angry if that is the case.”
He did not criticise Russian leader Vladimir Putin and redirected attention to China.
Mr Trump said: “It is interesting that everybody is always mentioning Russia. I don’t mind you mentioning them, but China at this point is probably a nation that you should be talking about much more so than Russia, because the things that China is doing are far worse.”
Mr Navalny, an anti-corruption activist, fell ill on a flight to Moscow on 20 August and was taken to a hospital in the Siberian city of Omsk after the plane made an emergency landing.
The 44-year-old was moved two days later to Berlin’s Charite hospital, where doctors said initial tests indicated Mr Navalny had been poisoned.
This week, the German government said that the Kremlin critic was poisoned with the same type of Soviet-era nerve agent used in a 2018 attack on a former Russian spy. The news provoked outrage from Western leaders who demanded Moscow provide an explanation.
The German government said that testing by a German military laboratory showed “proof without doubt of a chemical nerve agent from the Novichok group.” British authorities identified Novichok as the poison used on former spy Sergei Skripal and his daughter in England two years ago. NATO supported the findings.
The findings — which experts say point strongly to Russian state involvement — added to tensions between Russia and the West. German Chancellor Angela Merkel called Mr Navalny’s poisoning attempted murder, meant to silence one of Mr Putin’s fiercest critics.
The Berlin hospital treating the dissident said he remains on a ventilator though his condition is improving. It said it expects a long recovery and still can’t rule out long-term effects on his health from the poisoning.
Russia’s Foreign Ministry said on Saturday it had noticed multiple hostile statements directed at Russia on the topic of Mr Navalny’s health.
“In relation to these presumptuous comments that… (Novichok) was developed here, it is imperative to say the following,” the ministry wrote in statement.
“For many years, specialists in many Western and countries and in the specialised structures of NATO have worked with this wide-ranging group of chemical components.”
Wires contributed to this report