From the article:
These efforts come in spite of the 1981 Algiers Accords, which led to the release of American hostages seized from the U.S. Embassy in Tehran, in which the United States pledged to never again attempt to overthrow the Iranian government. The failure of the United States to honor this signed bilateral agreement has contributed to the Iranians' lack of trust in the U.S. government and overall anti-American sentiment in that country. 
Why should the United States honor an "agreement" that was signed under that kind of pressure and duress? You don't negotiate by taking U.S. hostages and then expect the results of said "negotiations" to be seriously honored later on.