The Midlands clubs announced on Tuesday (AEDT) it had terminated the head coach's contract in the wake of Sunday's 4-0 Premier League defeat to Chelsea, which left it with just two wins from 21 league games.
Guardiola admits he was disappointed by the news and said he hopes to be able to "drink a good red wine" with the 59-year-old in future.
"First, I can say a big hug for Tony, like before with [former West Ham boss Slaven] Bilic," he said.
"Today, it is like this. When I was young, they said in England they respected a lot the contracts and the managers were never sacked. Now, it is so, so difficult. Wherever, it is the same. We have to accept that, we know that.
"Everybody knows when we don't have results… managers here can win the Premier League and months later they will be sacked. You have to work within that situation.
"I am really disappointed because I have a great relationship with Tony Pulis. Every time we went against West Brom he was an amazing man, so gentle.
"Always, we would drink a good red wine. Hopefully we can do it again in the future."