The mayor said he seeks to prevent "political manifestations" from taking place at the cemetery amid Russia's continued invasion of Ukraine.
"No permits will be issued," he told BNS earlier this week. "If someone wants to celebrate the end of World War Two, May 8 is the day for that."
Lithuania, like many other European countries, officially marks the end of World War Two on May 8. Russians, however, usually celebrate the victory over Nazi Germany on May 9.
"Just because it is a cemetery does not mean that you can hold a political rally there," Simasius said. "Obviously, it is walking on the edge. I mean the rally with the [Russian] ambassador. It was more than just a tribute."
"We will give no legal grounds for this, and what the police will do is a separate issue," he added.
The mayor expects the parliament to adopt decisions by May 9 on outlawing the letter "Z" and the black and orange ribbon of Saint George, which have become symbols of Russia's war in Ukraine.
Municipal officials have told BNS that no requests for permits for any organized events on May 9 have been received so far. No permits are required for unorganized gatherings at the cemetery, but the municipality will still consult law enforcement on concrete steps.
"Vilnius City Municipality is considering various solutions that are most appropriate for this period of time, primarily in the context of Russia's war in Ukraine," the municipality has said.
"Consultations with law enforcement and special services are also planned. A decision will be made in the next week and we will announce it as soon as possible," it added.
The Lithuanian State Security Department (VSD) has warned of possible provocations and violent incidents during commemorations at Soviet soldiers' cemeteries on May 9.
Such commemorations are organized annually in various Lithuanian cities and towns by Russian diplomats together with Russian expatriates.
These events are usually attended by several hundred people wearing Saint George's ribbons which the Lithuanian parliament is planning to outlaw because of the war in Ukraine.
If the legislation is passed, wearing the black and orange ribbons and displaying the "Z" symbol of the Russian war in Ukraine will be punishable by law.