The Argentina captain's long-awaited transfer to the Spanish club is expected to be completed in the next 24 hours after the Reds accepted a suitable bid, having rejected a 16m offer last weekend.
When news of that approach reached the 26-year-old he backed out of playing in the Barclays Premier League defeat to Manchester City at Eastlands on Monday.
That severely disrupted Hodgson's plans and he hit out at the player's unprofessionalism.
"It is not easy for me to defend the actions (of Mascherano) because professionals are paid to play and when they are called on to play, they play," he said.
"We had a player at Blackburn, Graeme Le Saux, who was very agitated when I joined the club because he was determined to go to Chelsea and that caused a lot of problems in pre-season.
"Tim Sherwood was wanted by Tottenham and that caused a lot of problems because he wanted to get back to London.
"These situations do occur unfortunately and we have to live with it.
"I don't think they (the players) mean it as a challenge to your authority or a challenge to the club's authority.
"It is just a selfish situation that they have got something they want to do and they just expect the club, and, therefore, you as one of the leaders of the club, to bow down and accept that they are going to do it.
"Unfortunately, there are going to be periods of time when there will be some unpleasantness because players must also understand that when you sign contracts you sign contracts to play.
"If the club decide they are going to accept an offer for you and let you go that is one thing, but you run the risk the club might say 'I'm sorry, you've got the contract and we aren't selling you so you are staying'.
"It doesn't bother me as a challenge to my authority, it is just a fact of life.
"But it is a fact of life which gets exacerbated in a one-month period in January and between July and August when it is a time of year when a lot of people are trying to do their business."
Mascherano has agreed a four-year, 85,000-a-week contract and Barcelona expect him to undergo a medical in the next 24 hours.
"FC Barcelona and Liverpool FC have reached an agreement in principle to the transfer of Javier Mascherano for the next four seasons," a statement from the Catalan club said yesterday.
"The deal was closed after the intensive efforts made by the club in the last few hours and through the provision of the player himself engaged in the negotiation."
Hodgson has spent most of his time since taking over on July 1 talking about players who are leaving or reported to be leaving, the latest being Dirk Kuyt on Wednesday.
The Englishman dismissed that prospect out of hand despite Kuyt's agent claiming he wanted to move to Inter Milan and the player pledged his commitment to the club after Thursday night's 2-1 Europa League play-off victory over Trabzonspor.
"We have to be forgiven for getting irritated by agents stirring things up even more," said 62-year-old Hodgson, who has mixed feelings about the imminent closure of the transfer window as it will stop speculation about his players but leaves him little time to buy reinforcements.
"It is bad enough if there is a genuine offer and a genuine problem to solve but it is even worse when you are constantly batting away things you shouldn't even be talking about.
"When the window closes then every press conference is about football and football matters rather than 'X's agent is saying this and is there any truth in it?' and you are trying to diplomatically answer the question without offending too many people."
Hodgson is optimistic he can add players before the transfer window closes.
A deal is close for Fulham left-back Paul Konchesky but Hodgson also needs reinforcements up front to give Fernando Torres some back-up.
"We still need to improve our squad and we haven't much time to do that," said the Reds chief.
"I am hoping that in the short period left in the transfer window we still have the chance to add at least a couple of players in the squad to at least replace the ones who are no longer with us.
"With Mascherano going we are losing a lot of player and not bringing any in so it is not good in that respect."
Liverpool captain Steven Gerrard wants to win the Europa League even though he admits it is not the club's priority.
Ahead of tomorrow's home game against West Bromwich Albion, the England midfielder echoed the sentiments of Hodgson when he said the Premier League is the main focus after a disappointing seventh-placed finish last season.
But after four years without a trophy, Gerrard is keen to bring some silverware back to Anfield and knows Europe represents as good a chance as any.
After completing a 3-1 aggregate victory over Trabzonspor, for which the captain was left at home to recover from a back injury, the Reds have been pitted against Steaua Bucharest, Napoli and Utrecht in the group stages.
"It's a strong group and I'm certainly looking forward to the games," he said. "I'm confident we can get out of the group but it will be tough. The draw has given us some difficult challenges."