Aguero’s 14th minute opener meant that he reached the 100-goal milestone in just 147 matches – the second quickest in Premier League history behind Alan Shearer.
Newcastle equalised shortly afterwards to earn a deserved draw but Pellegrini was delighted with the impact Kun has had in his City career.
He said: “He deserves it because he makes an important difference. He’s a great technical player with a lot of power and I am very happy for him.”
Despite the lack of chances, Pellegrini was happy to leave St James’ Park with a point after facing a Newcastle side battling for Premier League survival.
“I’m happy because we started winning the game, but we didn’t have the control and we didn’t play very well but we knew before the game that it was a very difficult match,” he said.
“After the goal, we didn’t have so many chances, Newcastle didn’t create too many either but the draw was a fair result in the 90 minutes.
“Playing three days after a big game at the end of the season makes it hard to be 100%. The team was different also because we made some changes and that’s why the game was not the same.”
The Chilean was also pleased with Vincent Kompany’s return. The Belgian skipper started his first match in over a month and lasted the whole match without incident.
“He played well,” he said. “We didn’t have much defensive work to do but he played the 90 minutes and I spoke with him and he felt okay.”