Lithuanian-born Abromavicius was one of several outside experts brought in to help Ukraine's new government reform.
On Wednesday, he accused Ihor Kononenko, a lawmaker close to Poroshenko, of lobbying to get "his people" positions in government and as heads of state companies. Kononenko denied the accusations, suggesting Abromavicius was attempting to shift the blame for his failures, according to Reuters.
In a joint statement, Ukrainian ambassadors from the U.S., Canada, U.K., France, Germany, Italy, Lithuania, Sweden and Switzerland, said they were "deeply disappointed" by Abromavicius's resignation.
"Abromavicius and his professional team have made important strides, implementing tough but necessary economic reforms to help stabilize Ukraine's economy, root out endemic corruption, bring Ukraine into compliance with its IMF program obligations and promote more openness and transparency in government… It is important that Ukraine's leaders set aside their parochial differences, put the vested interests that have hindered the country's progress for decades squarely in the past, and press forward on vital reforms," the diplomats said in a statement published online.