Distinguishing the fundamental factors influencing long-term inflation trends from temporary shocks affecting short-term fluctuations around these trends is a critical issue for monetary policymakers. This distinction not only offers a clearer understanding of inflationary mechanisms but also provides a basis for designing optimal policies to control inflation across different time horizons. Consequently, accurately identifying and managing these factors is essential for achieving sustainable inflation stability and addressing short-term economic challenges. In this study, the factors influencing the long-term trend and short-term fluctuations of inflation in Iran’s economy during the period from 2008 to 2022 are examined using monthly macroeconomic data and selected global market variables. The Hodrick-Prescott filter is employed to separate the long-term trend from inflation fluctuations. Subsequently, machine learning models and feature importance analysis are applied to determine the impact of each identified factor. The results indicate that broad money growth is the most significant determinant of the long-term trend of inflation in Iran, accounting for approximately 80% of the variation. In contrast, the exchange rate is identified as the primary variable affecting short-term inflation fluctuations, though its contribution to the long-term trend is only 13%. These findings highlight the necessity of implementing sustainable policies to manage broad money growth in order to achieve inflation stability in Iran’s economy.