18 U.S.C. § 372 — Conspiracy to impede or injure officer

If two or more persons in any State, Territory, Possession, or District conspire to prevent, by force, intimidation, or threat, any person from accepting or holding any office, trust, or place of confidence under the United States, or from discharging any duties thereof, or to induce by like means any officer of the United States to leave the place where his duties as an officer are required to be performed, or to injure him in his person or property on account of his lawful discharge of the duties of his office, or while engaged in the lawful discharge thereof, or to injure his property so as to molest, interrupt, hinder, or impede him in the discharge of his official duties, each of such persons shall be fined under this title or imprisoned not more than six years, or both.

Federal felony

> by force, intimidation, or threat

You seem to be glossing over the key piece of that statute. Peaceful protest is protected by the first amendment (free speech, right to assembly).