It was not clear why they were returned a day after a US court order blocked Trump's ban on travelers and immigrants from seven predominantly Muslim countries, including Somalia.
Officials with the International Organization for Migration, which runs the transit center in Nairobi where the refugees had been waiting for their flights to the US, could not be reached for comment, Associated Press reported.
"How would you feel? One day you are telling friends bye, wishing them well, and the next you are back where you started," 28-year-old Nadir Hassan told The Associated Press by phone from the camp. "My home for 27 years was a refugee camp. I was hoping to start a new life in the US, get an education, a job, a life. We feel bad."
He had been on a waiting list to leave for about a decade, he said.
The fate of the Somali refugees is especially uncertain because Kenya's government has vowed to close their Dadaab camp, the world's largest, by the end of May, citing security concerns. Kenyan officials say the refugees will be returned to neighboring Somalia, where the al-Qaeda-linked al-Shabab extremist group continues to carry out deadly attacks in the capital, Mogadishu, and elsewhere.
The Kenyan government says al-Shabab uses Dadaab as a recruiting and training ground for extremists who attack Kenya, but it has not presented any proof.
Human rights groups have protested Kenya's plans to close Dadaab, saying some of the more than 250,000 refugees there have reported being pressured to leave the camp and that Somalia remains too unstable for people to return home. Refugees who have heeded Kenya's call to voluntarily leave have said they felt betrayed because assurances of safety and support went unfulfilled in Somalia.
A spokeswoman for the UN refugee agency, Yvonne Ndege, said Saturday the agency was looking at other ways of settling the refugees, including moving them to another camp in Kenya, Kakuma, which houses mostly people from South Sudan.