The Syrian President declared: “What you say is what you are.”
Mr Trump had insulted his counterpart in an 8 April tweet following a suspected chemical weapons attack in Douma.
He wrote: “Many dead, including women and children, in mindless CHEMICAL attack in Syria. Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world. President Putin, Russia and Iran are responsible for backing Animal Assad. Big price…”
He continued: “….to pay. Open area immediately for medical help and verification. Another humanitarian disaster for no reason whatsoever. SICK!”
In an interview with Russia Today, Mr Assad said he did not have a nickname or insult for Mr Trump: “This is not my language, so, I cannot use similar language. This is his language. It represents him.
“I think there is a very known principle, that what you say is what you are. So, he wanted to represent what he is, and that’s normal.”
Joint airstrikes on chemical weapons facilities were carried out by the US, UK and France following the alleged poison gas attack.
Mr Assad denied attacking his own people and said the attack would not have been in the government’s interest: “They told a story, they told a lie, and the public opinion around the world and in the West didn’t buy their story, but they couldn’t withdraw. So, they had to do something, even on a smaller scale.”
Mr Assad said the US must learn the lesson of Iraq and leave the country.
He also claimed the government had “started now opening doors for negotiations” with the Syrian Democratic Forces (SDF), a Kurdish dominated militia alliance that controls parts of northern and eastern Syria where US forces are stationed.
“This is the first option. If not, we’re going to resort to… liberating those areas by force,” he said, adding “the Americans should leave, somehow they’re going to leave”.
Speaking in English, Mr Assad said that direct conflict between his ally Russia and the US in Syria had been narrowly avoided.
“We were close to have direct conflict between the Russian forces and the American forces,” he said.
He said it was down to “the wisdom of the Russian leadership” that a confrontation did not happen.