TEHRAN, April 12 (Xinhua) -- Iran on Thursday blamed the U.S. and Israel for rising tension in the Middle East region, reaffirming its support for the Syrian government.

The gas attack allegations against the Syrian government result from the U.S. failure in the Arab country, a senior advisor to Iran's Supreme Leader Ali Khamenei said.

In an interview with Tasnim news agency, Ali Akbar Velayati slammed the U.S. allegations that the Syrian government launched a chemical attack in Damascus' suburban district of Douma, as "repeated and fabricated propaganda tricks" after the defeat of U.S.-backed militants in Syria.

Whenever the U.S.-backed mercenaries suffer a heavy blow in Syria, Washington resorts to recurring fabricated allegations of chemical attacks in Damascus, Velayati said.

Iran was committed to supporting the Syrian nation and its legitimate government, he said, adding that Iran would help strengthen the axis of resistance including Iran, Iraq, Syria and Lebanon.

U.S. President Donald Trump has threatened to launch a missile attack on Syria over the alleged gas attack in Douma, despite no evidence supporting the allegation.

On Thursday, the Syrian lawmaker Nashaat al-Atrash said the recent military victories by the Syrian army in Eastern Ghouta were the main reasons behind Trump's threat to attack Syria.

Al-Atrash pointed out that former U.S. President Barack Obama also threatened to take military actions against Syria over similar allegations, but did not execute his threat.

Even if Trump did, it could not disrupt the rapport among Syrian people, army and government, he said.

Also in the day, the Quds forces of Iran's Islamic Revolution Guards Corps (IRGC) warned of any Israeli offenses targeting Iran, semi-official Fars news agency reported.

"If you (Israel) equip Iran with the excuses (to retaliate), Tel Aviv and Haifa will be destroyed totally," Ali Shirazi, the representative of Iran's Supreme Leader in the IRGC's Quds Unit, said here on Thursday.

He advised the Israeli officials "to observe their behavior and not to do foolish act" by attacking Iran.

A day earlier, Israeli Prime Minister Benjamin Netanyahu warned Iran "not to test Israel's resolve" amid escalating tensions in the region.

Netanyahu said the attacks on Syria's Douma "show that confronting evil and aggression is a mission that is imposed on every generation."

Netanyahu's warning to Tehran came after Iran vowed to act in retaliation for an alleged Israeli airstrike on the T-4 Air Base in Syria, which killed at least 14 people, including seven Iranians.

On Thursday, Velayati also expressed hope that the Syrian army will liberate Idlib Province from the rebels, Press TV reported.

Following Syria's victory in Eastern Ghouta, the Arab nation's army will hopefully liberate Idlib, the major rebels bastion, Velayati said at a press conference in Damascus on Thursday.

He underlined the strategic significance of Idlib and hoped the northwestern province would be "liberated soon."

"East of the Euphrates is also a very important area. We hope big steps would be taken in order to liberate this area and expel the occupying Americans," Velayati said.

The Iranian official made the remarks following a meeting with the Syrian President Bashar al-Assad in Damascus on Thursday.

Iran, as the major regional ally of the Syrian government, has repeatedly vowed support for the Syrian government against the rebels and foreign forces.