Plaid has agreed a deal with Labour to allow the party to form a minority administration, which allowed Carwyn Jones to continue as first minister.
The agreement makes policy concessions to Plaid, but Ms Wood attacked Labour for being "arrogant".
She said Labour depended on her party's support, adding: "Why should we make it easy for them?"
Mr Jones was re-instated as first minister on Wednesday, following a deal which resolved the week-long deadlock over the position.
It followed a tied vote in the Senedd, in which Ms Wood was backed by the Tories and UKIP, while sole Lib Dem AM Kirsty Williams joined Labour in backing Mr Jones.
The Plaid leader told BBC Radio Wales: "There has been perhaps too much cosiness in the Senedd up to now."
"It was very easy for them to run a minority administration in the last term, when they could work with the Liberal Democrats or Plaid Cymru," she said, speaking to the Good Morning Wales programme.
Ms Wood said Labour was "not in that situation now, because of their actions last week in terms of what they said about us supposedly doing some sort of secret coalition with UKIP".
"They don't have that option of another party, they have to work with us, and why should we make it easy for them?"
In her Senedd speech on Wednesday, referring to the tied vote, Ms Wood said: "I'm not sorry for what happened last week and I will do it again if I have to make Labour realise that they are running a minority government.
"What we saw last week from that party was arrogance, it was complacency, and what we saw was a sense of entitlement on display.
"That vote happened because they refused to delay proceedings for just one week so that meaningful talks could take place. Well, we did get our week to talk, but it took some drama to get there."
There has been too much "cosiness" in the Senedd between the parties, Plaid Cymru leader Leanne Wood has said.