Is Physical Attraction or Appreciation of the Human Form Considered Attachment?

What you say "attachment", I think that the Pali word for 'attachment' is Upādāna:

In Buddhism, upādāna is a critical link in the arising of suffering.

When it says "link", there, it means that it is, "part of the causal chain of suffering",

In the twelve-linked chain of Dependent Origination (Pratītyasamutpāda, also see Twelve Nidanas), clinging (upādāna) is the ninth causal link:

• Upādāna (Clinging) is dependent on Tṛṣṇā (Craving) as a condition before it can exist.
  "With Craving as condition, Clinging arises".

That Wikipedia article (as well as other references, like this one) also says that there are different types of attachment:

In the Sutta Pitaka, the Buddha states that there are four types of clinging:

• sense-pleasure clinging (kamupadana)
• wrong-view clinging (ditthupadana)
• rites-and-rituals clinging (silabbatupadana)
• self-doctrine clinging (attavadupadana).

Perhaps you can see how "physical attraction" might be related to all four types of clinging; for example:

• "That person looks and feels and smells and sounds pleasurable, I enjoy perceiving them" (sense pleasure)
• "I'll love that person forever" alternatively "It's just a one-night stand with no consequences" (wrong view e.g. eternalism or nihilism)
• The "dating game" and "marriage" as a source of happiness (rites and rituals)
• "I am attractive or unattractive, because I do or don't have a romantic partner" (self-doctrine)

The Upadana Sutta says,

In one who keeps focusing on the allure of clingable phenomena (or: phenomena that offer sustenance = the five aggregates), craving develops. From craving as a requisite condition comes clinging/sustenance.

Now, in one who keeps focusing on the drawbacks of clingable phenomena, craving ceases. From the cessation of craving comes the cessation of clinging/sustenance. From the cessation of clinging/sustenance comes the cessation of becoming. From the cessation of becoming comes the cessation of birth. From the cessation of birth, then aging, illness & death, sorrow, lamentation, pain, distress, & despair all cease. Such is the cessation of this entire mass of suffering & stress.

I think that the first paragraph is saying that attachment arises as a result of a process like the following:

• "That person is physically attractive" (is focus on the allure of clingable phenomena)
• "I enjoy the attraction, I like being attracted" followed by "That enjoyment/attraction has vanished, I wish it would reoccur" (is craving)
• "I want that person, because they're attractive" (is attachment)

Conversely the second paragraph is recommending a process like the following:

• "Sensual pleasures are impermanent and cannot be satisfactory (focus on the drawbacks of clingable phenomena ... not only sensual pleasures but the other types of clinging too)
• "Seeing their drawbacks therefore I don't actually find them very attractive" (craving ceases)
• I'm not attracted so I don't become attached (no attachment so the cycle doesn't continue).

There are mental exercises purposely designed to make the body seem unattractive (e.g. imagine it as a corpse, as a skeleton, etc.).

I think there are also other ways to approach the problem. One way might be via self-doctrine, for example, if you have the thought, "I want that person, because they're attractive" then you might think ... "Wait, it's not that 'they are attractive' it's that 'I perceive them as, I consider them, I find them to be, attractive. However 'I' am impermanent, the 'I' is just a reification of impermanent senses, and so that (i.e. 'my' view, that they are attractive) is impermanent and not something to 'attach myself' to."

In Thundering Silence: Sutra on Knowing the Better Way to Catch a Snake by Thich Nhat Hanh, he writes,

Many people think that to undergo spiritual discipline is to practice asceticism and austerities. But to others, the practice of the Dharma does not exclude the enjoyment of the fresh air, the setting sun, a glass of cool water, and so on. Enjoying things in moderation does not bring us suffering or tie us with the bonds of attachment. Once we recognize that all of these things are impermanent, we have no problem enjoying them. In fact, real peace and joy are only possible when we see clearly into the nature of impermanence.

It then mentions times in the suttas where the Buddha expressed appreciation for a good meal, or commented on the beauty of a landscape.

Thich Nhat Hanh is a Zen Buddhist monk.

I think he's saying that perceiving a sense-pleasure as unpleasurable isn't the only way to avoid craving and attachment: that you may be able to avoid attachment by enjoying such things in moderation and remaining mindful of impermanence.

Beware though that doctrine may warn there's a difference between food and sex (if "sex" is what you mean by "physical attraction and appreciation of the human form") -- e.g. the Bhikkhuni Sutta,

This body, sister, comes into being through food. And yet it is by relying on food that food is to be abandoned.

This body comes into being through craving. And yet it is by relying on craving that craving is to be abandoned.

This body comes into being through conceit. And yet it is by relying on conceit that conceit is to be abandoned.

This body comes into being through sexual intercourse. Sexual intercourse is to be abandoned. With regard to sexual intercourse, the Buddha declares the cutting off of the bridge.

Buddhist monks (at least, if not lay people) are celibate.