Trading platform Tradeweb lifted the restrictions on Greek government bonds on Monday, following a request from the UK's Financial Conduct Authority, a spokesperson said.
Trading was suspended in June.
The Hellenic Capital Market Commission said earlier it had reopened the electronic secondary market HDAT for government bonds, operated by the Bank of Greece.
Greek 10-year bond yields were 2 basis points higher on the day at 12.13 percent. Five-year credit default swaps fell to 1,799 bps from 1,993 bps on Friday, according to data provider Markit.
Greece's stock market plunged nearly 23 percent on Monday when it opened after a five-week shutdown.