No, according to reporting, they wanted everyone to know about it the hacks well in advance. Republicans wanted it kept quiet.
There were reports and concerns going back to 2015. In September, there was an official finding by the CIA (but not a unified finding by all 17 national security agencies because of disagreements on some of the details) that they were hacking, and hacking to influence a particular result (Trump). The Obama administration was grappling for some time with how to deal with this without appearing to be trying to skew the results, themselves. With the official finding and report, they felt that a unified, bi-partisan approach would be the way to go.
One difference between September and now that would account for the stronger statements, and not just the election result, is that our intelligence agencies have had more time to gather and analyze information.
In September, there were all the leaks of DNC and Clinton-related emails from hacks. They knew one side had been breached, they also knew there were some minor confirmed breaches on the other side, and several thwarted attempts. The GOP claimed the one-sided nature of the leaks was because their information was better secured.
What came out more recently is that intelligence agencies were able to confirm that the GOP was also breached/hacked in a similar manner, and much more information was taken. It's this information - that both sides were compromised, but only one side seems to have had their information leaked, that lead to the greater confidence of malicious, one-sided intent.
Agency briefers told the senators it was now "quite clear" that electing Trump was Russia's goal, according to officials....
All the Democrats were on board for a joint statement, and a few of the Republicans were. Only a couple Republicans were against, but one of them was Mitch McConnell who said he'd claim partisanship and make a huge political stink if anyone said anything about it. Yes, the same McConnell who now claims it's important to get to the bottom of this.
To sum up - the White House knew about the hacking and wanted to make it known all along, but they also have much more information about intent that they couldn't support previously, so coming out with a stronger statement because they've gathered more proof, over time, can account for the fact that strong statements are being made after the election that weren't, before.
EDIT ALERT - had a typo in my quoted passage. Corrected it to say "NOW 'quite clear'", originally typed as "not 'quite clear'". That's a bit of a difference. Sorry about that.