No one was injured in the blasts, which caused damage to two of the party's offices in the north of the Armenian capital.
"We think that this provocation was aimed at creating a tense political situation," Prosperous Armenia spokesman Baghdasar Mherian told RFE/RL. "Prosperous Armenia declares that it is against extremists and calls on everyone to conduct its political battle in a civilized way."
Mherian said the party has not been receiving any threats.
Armenian President Robert Kocharian ordered law enforcement agencies to swiftly investigate the incident.
Prosperous Armenia was founded in 2005 by wealthy businessman Gagik Tsarukian and backs the president.
It is tipped to be the leading challenger to the ruling Republican Party in the May parliamentary elections.
Tensions between the two rival parties have increased in recent days, with scuffles reported between campaigning activists.