Gabriel Jesus shone with a goal and an assist in the first half on Wednesday as the visitors cruised to an emphatic victory less than a month after they had won 5-0 at London Stadium in the FA Cup.
Chelsea boss Antonio Conte was in the stands to watch the game, but Guardiola claims his managerial rival has nothing to be concerned about despite seeing City move to within 10 points of them.
"He doesn't have to be too worried because Chelsea are nine points ahead [of anyone else]," Guardiola said at his post-match media conference.
"Only they can lose the Premier League. The gap [to Chelsea] is too big, but we will until the last day be fighting to qualify for the Champions League.
"All the teams around us are so strong but we want to be up there with them."
Kevin De Bruyne and David Silva also scored for City, with Yaya Toure adding a fourth from the penalty spot in the second half as Guardiola celebrated only a second league win in five attempts.
He said: "The main difference in this game was the first time we had a chance to score, we took it and the second time we had a chance to score, we took it.
"After that the game wasn't over, but it was easier. We are still far away from the perfect, perfect performance.
"West Ham arrived in a good moment so of course, we are very happy. We won 3-0 on Saturday [in the FA Cup against Crystal Palace] then 4-0 here away from home and we were quite solid.
"We worked well with and without the ball and our three guys up front are so, so quick. We created a lot of chances too, so I am happy."
Slaven Bilic, meanwhile, was furious his West Ham side had played into City's hands by making individual mistakes so soon after their cup defeat to Guardiola's men.
"They were very dangerous, especially when we had the ball," said Bilic.
"We gave the ball away in the areas where they are going to punish you. It is hard to analyse this game, so quickly we were two down and then we conceded again through a mistake.
"Not every team you play is like Man City but we need more from us. When you give players like that space and time between the lines, they just slaughter you.
"They beat us 5-0 in the cup and then 4-0. Make no mistake, we have to give them credit but it was also about us.
"It was very frustrating and it is like what happened in the cup. We again started well but when you make mistakes like we did it is very difficult to play against them."