Guardiola said the pair’s agent, Mino Raiola, contacted him and told him the midfielders were available.
Pogba, who joined United for a then world record £89m in 2016, stayed at United as Mkhitaryan joined Arsenal.
Raiola told BBC Sport he did not speak to Guardiola but did not deny telling City of the players’ availability.
A senior United source said they would not have sold Pogba in January, and they would not have sold him or Mkhitaryan to City.
In his news conference before Saturday’s Manchester derby at Etihad Stadium – when City will win the Premier League if they beat their rivals – Guardiola was asked to comment on reports that Raiola called him “a coward” and a “dog” for the way he treats people.
Guardiola said: “Two months ago he offered me Mkhitaryan and Pogba to play with us.
“Comparing [me to] a dog is bad – it’s not good. He has to respect the dogs.”