Citing security concerns, the authorities said if he doesn't depart on his own, he could be arrested and forcibly deported.
Philips, who was born in Jamaica and raised in Canada, spoke in Frankfurt earlier this week on the subject “Islam, the Misunderstood Religion” alongside German Islamist preacher Pierre Vogel – who authorities have no way to deport – after a court allowed the event over the objections of Frankfurt officials.
Arid Uka, the 21-year-old Kosovar who has admitted to killing two US airmen in Frankfurt in March, is thought to have established contact to radical Islamist preachers including Vogel before the shooting.
Police said up to 1,500 people, separated by gender, attended the rally, where Philips appeared as a surprise guest. The 64-year-old has been on a tour of sorts around Europe, recently surfacing in Denmark.
Although Philips has failed to deliver extremist messages during his European appearances, he's attracted plenty of protesters, including 500 in Frankfurt.
Philips, who runs an online university has attracted the ire of officials for his previously inflammatory messages and alleged links to Muslim extremists.
He is alleged to have preached that homosexuals should received the death penalty, although in Frankfurt he said he doesn't hate gays at all.
In previous interviews he has also accused Western governments of oppressing him by falsely associating him with terrorism.