The Thai student, who has not been identified, was taken into custody by Egyptian authorities on Sept 24 in Cairo.
Photos allegedly linked to Daesh were discovered on his mobile phone, the Thai embassy in Cairo said on its official Facebook page.
However, Thai Prime Minister Prayuth Chan-ocha played down any Daesh links and said he had instructed relevant agencies to follow the case and provide assistance to the student.
"There has been constant monitoring and there are no links here with any foreign group," Prayuth told reporters.
"The Thai ambassador in Cairo has met with the Egyptian deputy foreign minister asking for help and the Egyptian promised to follow up the case and cooperate with Thailand, we will not leave anyone behind," he said, Reuters reported.
The arrested student has previously been detained in Sudan and had moved to Egypt because he could not continue his studies in Sudan, said deputy prime minister Prawit Wongsuwan, who oversees security and intelligence agencies. Prawit added that there are currently no Daesh activities in Thailand.
Thailand is predominantly Buddhist except in the three southern provinces of Pattani, Yala, and Narathiwat, which are 80 percent Muslim. There are also pockets of Muslim communities in large Thai cities.
The three provinces, and a small part of neighboring Songkhla province, were historically part of a Malay Muslim sultanate annexed by Thailand in 1909 and separatist tensions have simmered since then.
Almost 7,000 people have been killed in the last round of insurgency that has raged since 2004.