"I clearly liked the player enough to stay in touch with his agent over the wintertime," Cashman said. "If we can get through a whole bunch of other steps, I'll have more to speak to."
The 36-year-old right-hander said early Monday that he has already reached a deal with the Yankees, holding a press conference in Seoul, Korea. Park's signing cannot be officially acknowledged until he passes a physical, but a club source confirmed the agreement.
He was 3-3 with a 4.43 ERA in 45 games -- including seven starts -- for the Phillies last season, pitching in the World Series against the Yankees. The contract is reported to be for $1.2 million, with incentives that could net an extra $300,000.
"He's very attractive, especially what he does out of the bullpen," Cashman said. "He's got a good arm and we saw it in the World Series."
According to the Korea Times, Park said that he had been considering the Cubs and Yankees, and until recently had been leaning toward Chicago because they would offer him an opportunity to compete for the starting rotation.
"I was deliberating on the Chicago Cubs and the Yankees, but their history and championship contention resulted in me picking the Yankees," Park said. "Until last night, I was leaning toward the Cubs."
He said that the opportunity to win a World Series this late in his career influenced his decision.
"I wanted to play for a champion-caliber team this year again," Park said. "I am not certain how much longer I will play baseball, but it will be a huge experience and memory to play with the Yankees."
Park is expected to pitch in relief for the Yankees and should not be under consideration for the fifth-starter's job, which has a packed set of candidates including Joba Chamberlain, Phil Hughes, Alfredo Aceves, Chad Gaudin and Sergio Mitre.
"He's pitched very well out of the bullpen," Yankees manager Joe Girardi said. "He's one of those guys you wouldn't really consider a one-inning guy. ... The one thing that we will do here, we'll make sure that we'll take what we feel is the best 12 [pitchers] and put them in their spots. Having more quality arms than spots in your camp is a luxury. It's our job to try and make the right decisions."
The signing could potentially open up a trade opportunity for the Yankees, who will need to clear room on their 40-man roster for Park. Cashman said that he did not necessarily see the bullpen as an area of concern.
"I think we have a terrific bullpen," Cashman said. "The more, the merrier. You can never have enough."
Against the Yankees in last year's World Series -- his debut in the Fall Classic -- Park had three strikeouts in 3 1/3 scoreless innings over four appearances.
Park has pitched in 16 Major League seasons with the Dodgers, Rangers, Padres, Mets and Phillies. He has a career record of 120-95 and a 4.35 ERA in 423 big league games (287 starts).
Bryan Hoch is a reporter for MLB.com. Thomas Harding, a reporter for MLB.com, contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.