Perhaps the show was referencing Muhammad Al-Ghazali? Not the 20th century scholar but the medieval theologian known more commonly by his kunya Abu Hamid al-Ghazali.

There are not quotes from the Prophet Muhammad about Greek philosophy. The controversies about Greek philosophy arose centuries after his death. Furthermore, had such a saying existed, the critics of Greek philosophical influence would have quoted it over and over again. The fact that that didn't happen is a pretty strong indication that there was no such quote. Perhaps the show confused a scholar or theologian named Muhammad (very common name) with the Prophet Muhammad.

This is a standard enough response that I almost feel like it should go in the FAQ but the basic fact is that we don't reliably have any quotations from Muhammad outside of the Quran.

The historiography of hadith is a complete mess and you will find the prophet quoted at various times to support every possible position and expounding upon the most trivial of disputes. Much of the analysis of these quotations is that they are fabrications, or, at best, that we simply can't discern the wheat from the chaff.

That said, having done a search through sunnah.com, which I believe is part of the leeds university Quranic corpus project (in any event it allows for searching of the six primary sunni books of hadith) there is no record of the prophet mentioning philosophy, falsafa, or kalam (in the sense of "Ilm al Kalam").

The only mentions of the greeks that I can find refers to them as the "rumi" i.e. the Byzantine Greeks, although it's possible that the Arabic of this time doesn't make the distinction as it does today.

All in all this makes sense, any reference by Muhammad to philosophy would almost certainly have been anachronistic, even the bible probably had not been translated into Arabic at this point. Kalam as a theological discourse did not arise until after his death and was not characterized by greek influences and we don't see any real effect of philosophy until the 9th century and the translation movement (although Greek as a language plays a much earlier role from at least the time of the Ummayad court in which official documents were often rendered in both Greek and Arabic.)

Source wise see the articles in the Encylopedia of Islam on Ilm al Kalam, Falsafa, Tardjama.

For information on why Muhammad's life is so difficult to pin down see Robert Hoylands "Writing the Biography of the Prophet Muhammad: Problems and Solutions."