However, he is willing to extend his stay if it means first-team football.
He said: "I've got to talk to both teams and see how things are. It was great to come to Bournemouth as it was a massive opportunity.
"It's first-team football I want and I would like to stay at Bournemouth and get it there, if I can't at Portsmouth."
Keene had only been on the pitch three minutes when he scored, coming on for the Cherries leading scorer James Hayter.
He bundled home Stephen Cooke's cross, just minutes after Chris Iwelumo had threatened to give host Colchester the lead but his left foot volley was denied by the post.