Russia has denounced last week's US attack on Syria and warned further such action would derail global security.
The US has said its strike on a Syrian air force base was in response to the Syrian government, which it blamed for launching a deadly chemical attack in the rebel-held town of Khan Sheikhoun in Idlib province that killed at least 87 people.
Russia has claimed the victims were killed by toxic agents released from a rebel chemical arsenal and has pushed for an international probe.
As he hosted his Iranian and Syrian counterparts in Moscow on Friday for a trilateral meeting focused on the Syrian civil war, Sergey Lavrov, the Russian foreign minister, said similar attacks would have "grave consequences not only for regional but global security".
"We have reiterated our position and were united in stating that the attack was an act of aggression, which blatantly violated the principles of international law and the UN Charter," Lavrov said.
"We call on the US and its allies to respect Syria's sovereignty and refrain from actions similar to what happened on April 7, and which have serious ramifications not only for regional, but also global security.
The three countries are calling for two investigations, an independent probe into the chemical attack and another investigation into the US missile strike.
Syrian Foreign Minister Walid Muallem welcomed international inspectors to visit the base, which Washington claimed had served as a platform for the attack.
"The Syrian government repeatedly said it does not have chemical weapons. That is because they were all seized in 2014. What happened in Khan Sheikhoun is a fabrication and the Syrian air force did not target anyone with chemical weapons.
"We did not use them against terrorist groups or on our own people. We condemn any use of chemical weapons," Muallem said.
In Russia's view, the preliminary probe conducted by the Organization for the Prohibition of Chemical Weapons, the UN's chemical watchdog, should be widened to include experts from many nations, said Lavrov.
"If our US colleagues and some European nations believe that their version is right, they have no reason to fear the creation of such an independent group," he said. "The investigation into this high-profile incident must be transparent and leave no doubt that someone is trying to hide something."
Rory Challands, reporting from Moscow, said Russia, Syria, and Iran were likely to be concerned the Tomahawk missile barrage could signal deeper US involvement in the Syrian conflict.
"Up until that missile strike, the US had essentially been reluctant to commit militarily against Syrian President Bashar al-Assad. It had kept itself fighting ISIL and supporting rebel groups on the ground," Challands said.
Lavrov met earlier this week with his US counterpart Rex Tillerson in Moscow for talks that also focused on the Syrian conflict.
Tillerson emphasised the need to rebuild US-Russian ties, but at the same time condemned Russia's support for Assad.
The United States has implicated the Assad government in crimes against humanity, including attacks on civilians with chemical weapons.
Assad said on Thursday the alleged poison gas attack in Khan Sheikhoun was a "fabrication" to justify a US military strike.