ISTANBUL — Iran on Monday launched missile strikes on what it said were Sunni Islamic extremist hideouts in eastern Syria, a move it portrayed as retaliation for a deadly terrorist attack on an Iranian military parade last month.

Iran’s Revolutionary Guard Corps said it fired six medium-range missiles into Syria from bases in western Iran at 2 a.m. local time, striking east of the Euphrates River and killing and wounding several militants. It said its combat drones then targeted the sites.

A statement on the Guard’s website described those killed as “takfiri terrorists,” a term it often uses to refer to the Islamic State. The militant group still holds pockets of territory in Syria’s Deir al-Zour province, where U.S. troops are assisting local fighters to defeat the extremists.

The strikes against the Islamic State on Monday, however, came even as Iran had blamed local Arab separatists for last month’s attack in the southwestern city of Ahvaz. At a military parade Sept. 22, gunmen killed at least two dozen people, including a 4-year-old boy. Iran identified the five perpetrators as residents of Ahvaz.

But both the Islamic State and a local separatist group claimed responsibility for the attack. Iran accused regional rivals Saudi Arabia and the United Arab Emirates of supporting the local Arab nationalists, who have fought for autonomy from Iran’s mainly ethnic Persian population.

Iran’s show of strength Monday appeared to be more about sending a message to its adversaries — in the region and abroad — than targeting those responsible for the assault.

At least four of the missiles landed in the Hajin area of eastern Syria, where the Islamic State is still active, according to the Britain-based Syrian Observatory for Human Rights. The Revolutionary Guard said the missiles traveled some 350 miles from Iran’s Kermanshah province to their targets in Syria. Iran, however, commands a number of loyal proxy forces in Syria that are stationed nearby.

The strikes also capped a week of Iranian diplomacy at the United Nations, where President Hassan Rouhani sought to rally European and other nations to oppose stepped-up U.S. efforts to target Iran.

According to Henry Rome, Iran associate at the Eurasia Group risk analysis firm, Rouhani did “not want an Iranian retaliation to dominate conversations” at the United Nations.

It is the second time in a month that Iran has fired medium-range ballistic missiles at militant groups in Syria and Iraq. Last month, Iran fired missiles at Kurdish militants based in Iraq.

Bijan Sabbagh contributed to this report.