The Galaxy played Colorado Rapids on Saturday night without four of their key players and were subsequently beaten 1-0 at the StubHub Center.
Skipper Robbie Keane (Republic of Ireland), defender Omar Gonzalez and star forward Landon Donovan (both USA) and goalkeeper Jaime Penedo (Panama) were all absent from the Galaxy squad because of national team duties with Arena suggesting that perhaps league games should take a backseat when internationals are on.
"It's ridiculous we have to play these games in these windows," Arena said.
"We have such a congested schedule. I don't think we've played Colorado yet this year with our [full] team, which is ridiculous.
"You know, you're in playoff races, and I think every time - I don't know if every time is a fixture window, but for whatever reason, we've not played them yet with our full team."