The ministry had issued a statement on January 22 warning against collecting donations for groups not registered with the government.
Seven Saudi citizens were arrested on Friday night while meeting in a house in the western port city of Jeddah, according to the spokesman.
Two other Saudis were detained in separate raids in Jeddah and the holy city of Medina.
He did not give the nationality of the tenth man held in custody.
The spokesman did not provide additional information on the detainees' identities, but said that they are under interrogation.
Speaking to Al Jazeera from Jeddah on Saturday, Mohammed Hasan al-Hashemi said that his brother brother, Saud al-Hashemi, was arrested on Friday evening for no reason.
He said: "My brother has no link to any terrorist organisation and his work was dedicated to charity as he travelled to Iraq, Afghanistan, Africa and Bangladesh to help people there.
"My brother used to work in public and has nothing to hide.
"I have no idea why he was detained and the Saudi authorities have not commented on his arrest.
"Dr Saud has received many certificates of gratitude from the Saudi government and other international organisations for his contribution to charity work."
Mohammed Hasan al-Hashemi appealed to "his majesty, our father, King Abdullah bin Abdulaziz, to release my brother as we live in a state of law".