Guardiola made a beeline for Guimaraes at the final whistle and exchanged words before making his way off the pitch. Guimaraes' teammate Joelinton was also ushered away from City's players by Newcastle staff as tempers boiled over.
City goalkeeper Gigio Donnarumma also clashed with Toon assistant manager Jason Tindall.
Asked about the fracas afterwards, Guardiola said: "I told him (Bruno) how good he is, and the situation with Gigio (Donnarumma) I told him what happened for the previous situations. I think it's fine."
Asked about Newcastle's intensity, he also stated: "I didn't complain about that.
"Newcastle is a top side, top players, top manager so unfortunately tonight we could not make the momentum that we had. It was an entertaining game, we both had chances, and then there was a momentum shift, and ultimately we couldn't win.
"Both keepers were good, and after we missed chances. It was an entertaining game with many chances. We were closer in the beginning."