"Self-isolation doesn't directly affect the president's work, there will just be no in-person events for some time," Peskov told journalists.
He did not specify how long the 68-year-old president will be self-isolating for and declined to say who in Putin's entourage had tested positive.
Later on Tuesday, Putin was due to meet with the leadership of the ruling United Russia party ahead of parliamentary polls on 17-19 September.
It is unclear whether he will be in self-isolation throughout the election week-end.
Russian authorities have taken exceptional measures to protect Putin -- who says he has been vaccinated with Russia's homegrown Sputnik V jab -- since the start of the pandemic.
Foreign leaders, journalists and officials have all been required to self-isolate in advance of being in contact with Putin and a disinfection tunnel was installed at his residence outside Moscow.
The Russian leader said in late June that he was vaccinated with Sputnik after months of secrecy around the issue, but the Kremlin did not show images of the inoculation.
In recent months, the longtime Russian leader had resumed his work trips and face-to-face meetings, but many of his contacts are still required to spend two weeks in quarantine.
Putin on Monday met with Syrian president Bashar al-Assad and with Russian athletes returning from the Tokyo Paralympic Games.