Bulgarian Prime Minister Boyko Borisov has said President Rosen Plevneliev made a mistake by "playing the hawk" on Russia and straining Sofia-Moscow relations.

Borisov has told reporters, quoted by the government's press service, that the current cabinet has managed to normalize ties.

"His mistake was that, by playing the hawk - and I have said this to him [privately] and publicly to a certain extent - worsened our relations with Russia," he has argued.

"Now I think with the benevolence we are having both I and president [Vladimir] Putin and [Prime Minister Dmitry] Medvedev have managed to fix things."

Plevneliev, who is into the last few months of his term of office (he is not running for a second one), has often left Bulgarians divided by issuing harsh statements with regard to Russia's leadership and Russian actions in Crimea and Eastern Ukraine.

Rifts appeared in Sofia-Moscow relations even before Plevneliev took over as Borisov, in his first tenure, began abandoning major energy projects involving Russian companies.

Since taking office again, however, the Prime Minister has sought to improve relations.

"I am optimistic due to the benevolent tone and the desire to untie the knots that were formed so far," Borisov is quoted as saying as a comment on a recent conversation he held with Putin over the phone.

The next president should be "moderate" and have good relations with all states, Borisov has added, a day after unveiling the name of Parliament Speaker Tsetska Tsacheva as his party's presidential candidate.

In 2011, Plevneliev's presidential nomination also came from GERB.